Volvo D13 engines provide hundreds of diagnostic trouble codes (DTCs), and though the number is large, the significant percentage of codes account for a large number of customer service calls outside the repair shop. Using current search patterns and experience from both the workshop and the technician, some of the most common Volvo D13 fault codes that are being investigated include P029900, P20EE00, P205B64, P042000, P040100, P008700, P030000, P030100, P220013, P207F00, and P207F9A.

These codes tend to be linked with the turbocharger, SCR/DEF aftertreatment system, EGR system, fuel pressure, catalyst efficiency, NOx sensors, and the performance of engine combustion. If left unresolved, many of them can lead to engine derates, reduced performance, higher fuel consumption, increased emissions, and expensive downtime. Although ECM codes are reported separately, they more often than not indicate symptoms of one of several potential problems common to multiple engine systems.

Common Volvo D13 Fault Codes Explained: P029900, P20EE00, P205B64, P042000, P040100 and More

Why We Decided to Cover These Volvo Fault Codes

If you own or operate a Volvo VNL, VNR, VHD, or any truck powered by a Volvo D13 engine, you've probably encountered at least one of these fault codes.

At DrunkLab, we regularly receive support requests related to Volvo engine codes such as P20EE00, P029900, P205B64, P207F00, P207F9A, and P040100. Many of these diagnostic trouble codes are searched hundreds of times every month by truck owners trying to understand why their truck suddenly entered derate mode, lost power, illuminated the check engine light, or began displaying DEF-related warnings.

The problem is that a fault code rarely tells the complete story. A single DTC can be triggered by several different mechanical, electrical, or software-related issues. Likewise, one failed component—particularly within the emissions system—can generate multiple fault codes simultaneously. When expensive components are replaced based on inactivity due to stored fault codes, repairs are often considered avoidable and do not actually solve the root problem.

This guide explains what these Volvo D13 fault codes mean, why they occur, how frequently they appear in real-world service, and what diagnostic steps should be performed before replacing major components.

Most Common Volvo D13 Fault Codes

Volvo Fault Code P029900

What does P029900 mean?

P029900 is a code indicating the turbocharger was underboost. In not so technical language, the ECM has an indication that the engine is not creating the boost pressure that is required in the current operating conditions.

In practice, this code is frequently associated with turbo lag during acceleration, particularly when boost leaks, sticking VGT vanes, charge-air restrictions, or exhaust leaks prevent the turbocharger from reaching the requested pressure. While many operators immediately suspect a failed turbocharger, the actual cause is often found elsewhere in the intake or exhaust system.

Common symptoms

• Reduced engine power

• Poor acceleration

• Noticeable turbo lag

• Increased fuel consumption

• Check engine light

• Possible engine derate

Common causes

• Boost leaks

• Damaged charge air cooler

• Faulty turbocharger

• Sticking VGT mechanism

• Failed boost pressure sensor

• Exhaust leaks

• Charge-air piping leaks

• Restricted air intake

How common is it?

P029900 is a Volvo D13 fault code that is reported fairly often, and is most commonly associated with higher mileage trucks, where the wear and tear on the turbochargers, the deterioration of the charge-air hoses, and various leaks in the intake become more widespread.

Possible solutions

Begin with a complete boost-pressure leak test before replacing the turbocharger. Inspect charge-air piping, intercooler connections, VGT operation, intake restrictions, and boost-pressure sensor readings. In many cases, correcting an air leak or resolving a sticking VGT mechanism eliminates the fault without requiring turbocharger replacement.

Volvo Fault Code P20EE00

What does P20EE00 mean?

P20EE00 means that SCR efficiency is less than the relevant setpoint configured in the ECM. To put this in driveable terms, the ECM is saying that adequacy of SCR aftertreatment to mitigate NOx emissions is not at a level that would allow the ECM to expect that the engine will operate in conformance with the emission standards that govern the operation of the engine.

Although this fault is often described simply as a "bad SCR catalyst," the catalyst itself is not always the root cause. The ECM evaluates overall NOx conversion efficiency using information from upstream and downstream NOx sensors. Inaccurate sensor readings, contaminated DEF fluid, wiring issues, DEF dosing problems, as well as other aftertreatment issues can be an indication that the P20EE00 fault is set.

Common symptoms

• Check engine light

• DEF warning messages

• Progressive engine derates

• Reduced vehicle speed

• SCR system warnings

Common causes

• Failed NOx sensors

• DEF dosing problems

• SCR catalyst deterioration

• Poor-quality or contaminated DEF

• Wiring issues

• DEF injector restrictions

• Software calibration inconsistencies

How common is it?

P20EE00 is one of the most searched Volvo D13 fault codes among specialist. It continues to be one of the leading causes of emission-related derates. It especially occurs along with DEF faults and quality issues, NOx sensor faults, and catalyst efficiency codes.

Possible solutions

Proper diagnosis should include verifying NOx sensor performance, checking DEF quality, inspecting the DEF dosing system, evaluating SCR catalyst efficiency, and confirming that the entire aftertreatment system is operating correctly before replacing major components.

Volvo Fault Code P205B64

What does P205B64 mean?

P205B64 means an electrical fault has occurred in a sensor in the circuit of the DEF tank temperature sensor. The ECM has determined that it is impossible for a valid, correct, or complete signal to be sent to the ECM by the temperature sensor in the DEF tank circuit. As a result, the ECM will not be able to monitor the temperature of the DEF tank.

Unlike a simple temperature reading outside the expected range, this code specifically points to a problem within the sensor circuit itself. Since DEF temperature plays an important role in SCR system operation—particularly during cold-weather starts—the ECM may limit aftertreatment performance until reliable sensor data is restored.

Common symptoms

• DEF system warning messages

• Check engine light

• Potential engine derate

• Cold-weather DEF system issues

• SCR performance warnings

• DEF heating system abnormalities

Common causes

• Failed DEF tank temperature sensor

• DEF header assembly failure

• Damaged sensor wiring

• Corroded electrical connectors

• Open or shorted sensor circuit

• Water intrusion into connectors

How often does it occur?

The Volvo D13 trucks with P205B64 have started to become more prevalent. One of the primary reasons has to do with how these trucks start to accumulate mileage. Some of the other reasons deal with how the electrical connections on the trucks start to lose contact and how the electrode assembly starts to corrode.

Possible solutions

First, look at the DEF header assembly and verify the sensor wiring and electrical connectors. Confirm continuity of the circuit and verify the operation of the sensor before performing any repairs. Since the temperature sensor is often integrated into the DEF header, replacement of the complete assembly may be required if the sensor itself has failed.

Volvo Fault Code P042000

What does P042000 mean?

P042000 shows that the catalyst efficiency is limited. The ECM has made a diagnosis about the performance of the aftertreatment catalyst. The analysis determines that the normal operating conditions of the vehicle do not allow the performance of the aftertreatment catalyst to be efficient.

Although P042000 is often confused with P20EE00, the two codes evaluate different aspects of the aftertreatment system. P20EE00 looks at the efficiency of SCR NOx conversion. P042000 looks at the overall performance of catalysts. A degraded catalyst substrate, an incorrect sensor reading, and continuous aftertreatment faults can all result in this diagnostic code.

Common symptoms

• Emissions system fault messages

• Check engine light

• Potential engine derates

• Reduced aftertreatment efficiency

• Increased NOx emissions

• SCR-related warning messages

Common causes

• Catalyst aging

• Catalyst substrate deterioration

• NOx sensor inaccuracies

• SCR system faults

• DEF dosing problems

• Exhaust leaks upstream of the catalyst

How common is it?

P042000 occurs less than P20EE00. However, it does occur more frequently than P042000 on trucks with a lot of miles and where the engine catalysts slowly begin to lose effectiveness. It may also appear with SCR and NOx sensor fault codes and a decline in NOx sensor effectiveness.

Possible solutions

A complete aftertreatment diagnosis should always be performed before replacing the catalyst. Test NOx sensor function and examine the DEF dosing system. Also, confirm exhaust temperatures are within the correct range. Finally, assess the efficiency of the SCR. The catalyst should be the source of the issue.

Volvo Fault Code P040100

What does P040100 mean?

P040100 indicates an inadequate amount of Exhaust Gas Recirculation (EGR) flow. The ECM has indicated that the quantity of Exhaust Gas being recirculated does not agree with the quantity of Exhaust Gas being recirculated that the ECM expects based upon the current operating conditions of the Engine.

In many cases, the problem is not caused by the EGR valve itself. Carbon accumulation throughout the EGR system—including the valve, cooler, crossover piping, and differential pressure passages—is one of the most common real-world causes of this fault, particularly on high-mileage Volvo D13 engines.

Common symptoms

• Rough engine operation

• Increased soot production

• Reduced fuel economy

• Check engine light

• Poor throttle response

• Elevated exhaust temperatures

Common causes

• Stuck EGR valve

• Carbon buildup inside the EGR system

• Restricted EGR cooler

• Faulty EGR differential pressure sensor

• Damaged sensor tubing

• Wiring issues

• Electrical connector faults

How common is it?

P040100 code is a Volvo D13 engine diagnosed by the common EGR related trouble code. Urban transport trucks are mostly susceptible due to the fastest EGR System carbon accumulation. Long periods of stop-and-go or idle conditions are the most damaging operating profiles for an EGR System.

Possible solutions

Inspect the EGR valve, EGR cooler, crossover piping, differential pressure sensor, and associated tubing for restrictions, excessive soot deposits, or mechanical failures. Proper EGR flow can be restored by simply cleaning carbon-contaminated components. Major component replacements become unnecessary. Electrical circuits and sensor operation should also be verified before replacing expensive EGR hardware.

Volvo Fault Code P008700

What does P008700 mean?

P008700 describes fuel rail pressure is insufficient compared to the ECM’s expected value. The engine management system is in charge of continuously checking the rail fuel pressure to make sure that the fuel is properly sprayed by the injectors and that the combustion is efficient. If the actual fuel pressure is below the calibrated value, the ECM sets a P008700 fault code, and may restrict engine power in order to protect the fuel system.

Although the fault often points toward a fuel delivery problem, the underlying cause may originate anywhere between the fuel tank and the high-pressure fuel rail.

Common symptoms

• Hard starting

• Loss of engine power

• Poor acceleration

• Check engine light

• Engine hesitation under load

• Possible engine shutdown

• Engine derate in severe cases

Common causes

• Restricted fuel filters

• Weak fuel supply pump

• High-pressure fuel pump wear

• Fuel leaks

• Low fuel pressure sensor faults

• Air entering the fuel system

• Fuel line restrictions

Potential consequences

Fuel pressure problems should never be ignored because they directly affect injector performance and combustion quality. Continued operation with insufficient fuel pressure may lead to difficult starting, poor engine performance, injector damage, and unexpected engine shutdown.

Possible solutions

Check fuel filters first, then check fuel supply pressure, the performance of the high-pressure pump, the leakage of injectors, and the accuracy of the sensors, before you replace any of the major components of the fuel system.

Volvo Fault Codes P030000 and P030100

What do these codes mean?

These diagnostic trouble codes indicate that the ECM has detected engine misfires during combustion.

P030000 typically corresponds to a random misfire or to multiple misfires from multiple cylinders. In such cases the ECM (Engine Control Module) cannot pinpoint the problem to a specific cylinder.

P030100 provides a unique case of a misfire found in Cylinder 1. This enables technicians to shorten the diagnostic process.

Although these codes are often linked to issues associated with fuel injection, they are also the result of the loss of compression, the presence of an electrical problem, the issue of fuel delivery, or an overall problem that pertains to the quality of combustion.

Common symptoms

• Rough idle

• Engine vibration

• Reduced power

• Increased fuel consumption

• Hard starting

• Check engine light

• Excessive exhaust smoke under certain conditions

Common causes

• Injector malfunction

• Fuel delivery problems

• Low cylinder compression

• Valve train issues

• Wiring faults

• ECM driver faults

• Air entering the fuel system

How common are these codes?

Misfire-related fault codes occur less frequently than emissions-system faults but can become increasingly common on higher-mileage engines where injector wear and fuel system degradation begin affecting combustion quality.

Possible solutions

Diagnosis should include injector balance testing, fuel pressure verification, compression testing, valve train inspection, and electrical testing before replacing injectors or engine components.

Volvo Fault Code P220013

What does P220013 mean?

P220013 is pointing to an issue relating to the NOx sensor circuit due to an electrical fault. Rather than simply reporting inaccurate emissions readings, the ECM has detected an abnormal electrical condition such as an open circuit, short circuit, loss of communication, or an implausible signal from the NOx sensor.

Modern Volvo D13 engines rely heavily on NOx sensor feedback to control SCR operation and verify emissions-system efficiency. Because the ECM continuously compares NOx levels before and after the SCR catalyst, a single electrical fault in the sensor circuit can affect multiple aftertreatment functions and eventually trigger additional emissions-related fault codes.

Common symptoms

• Check engine light

• SCR warning messages

• DEF-related fault codes

• Engine derate

• Reduced emissions-system performance

• Increased NOx emissions

• Limited vehicle speed after progressive derates

Common causes

• Failed NOx sensor

• Open circuit in the NOx sensor wiring

• Short circuit

• Corroded electrical connectors

• Sensor heater failure

• CAN communication issues

• SCR system faults affecting sensor operation

How common is it?

NOx sensor failures remain one of the most common emissions-related problems found on Volvo D13 engines. As trucks accumulate mileage, exposure to high exhaust temperatures, vibration, moisture, and road contaminants significantly increases the likelihood of sensor and wiring failures.

NOx sensors perform key functions in SCR diagnostics which is why P220013 often accompanies P20EE00, P042000, P207F00, or P207F9A. Therefore, when one of these components is due to be replaced, a complete diagnosis of the aftertreatment system must be performed first.

Possible solutions

Begin by inspecting the sensor wiring harness and electrical connectors for corrosion, broken wires, or damaged insulation. Verify sensor power supply, ground, communication circuits, and heater operation before replacing the NOx sensor. Verify appropriate operation of the SCR after repair and clear any related emission-system fault codes to prevent any secondary faults from being active.

Volvo D13 Fault Code P207F00

What does P207F00 mean?

P207F00 shows that the ECM has determined that the quality of DEF (Diesel Exhaust Fluid) is below the required specification, or that the SCR system cannot confirm the performance of DEF. The code points to the ECM not being able to verify the performance of DEF, not to a particular failed component. The DEF cannot achieve the expected level of reduction of NOx when it is sprayed into the exhaust stream.

Causes of P207F00 can include SCR efficiency, faulty NOx sensors, defective DEF dosing, and software balance. Ultimately, contaminated or diluted DEF is a frequent cause as well. The ECM ascertains the entire aftertreatment system, which allows the true cause of the problem to be beyond the DEF tank.

Common symptoms

• Check engine light

• DEF quality warnings

• SCR fault messages

• Engine derate countdown

• Reduced vehicle performance

• Increased NOx emissions

• Limited vehicle speed if the fault remains active

Common causes

• Contaminated DEF fluid

• Incorrect DEF concentration

• DEF tank contamination

• Faulty DEF quality sensor

• DEF dosing injector malfunction

• Failed NOx sensors

• SCR catalyst efficiency problems

• Software or calibration inconsistencies

How common is it?

P207F00 is among the most ubiquitous DEF-related fault codes on the Volvo D13 engine. This code appears in conjunction with P20EE00, P205B64, and/or P220013 codes. They often appear with multiple codes in conjunction with the starting of the deterioration of multiple after-treatment system components.

Possible solutions

Verify DEF concentration and fluid quality before replacing components. Continue diagnosis by evaluating NOx sensor operation, DEF dosing performance, SCR catalyst efficiency, and related electrical circuits. Fixing the source error but leaving the code as is will usually result in the bug appearing again after multiple drives.

Volvo D13 Fault Code P207F9A

What does P207F9A mean?

P207F9A is a code that is related to the quality of DEF, which is a diagnostic trouble code that is found on Volvo D13, D11, and D16 engines, and on Volvo FH, FM, FE, VNL, VNR, and other supported platforms. The ECM has determined that DEF quality cannot be verified or that the SCR system is unable to achieve the expected emissions reduction despite normal operating conditions.

Although similar to P207F00, this code is often associated with extended SCR performance verification routines and may require several operating cycles before it clears after repairs have been completed.

Common symptoms

• DEF warning lamp

• Check engine light

• SCR fault messages

• Engine derate

• Limited vehicle speed

• Reduced aftertreatment efficiency

Common causes

• Poor-quality DEF fluid

• Water-contaminated DEF

• DEF quality sensor issues

• Failed NOx sensors

• SCR catalyst deterioration

• DEF dosing system malfunctions

• Wiring or communication faults within the SCR system

How often does it occur?

P207F9A has become increasingly common on higher-mileage Volvo trucks. P210012 is McLaren’s way of saying “We don’t have enough data to make a determination.” P210012 will appear when P20EE00, P220013, or P205B64 are also present.

Possible solutions

Inspect DEF quality first, followed by the complete SCR system. Verify NOx sensor operation, dosing accuracy, DEF pressure, injector performance, and catalyst efficiency before replacing expensive emissions components.

Why SCR and DEF Fault Codes Often Appear Together

Volvo D13 diagnostics can be quite intricate, especially considering SCR and DEF fault codes often come bundled together. The aftertreatment system is built to be a self-containing network of sensors, control modules, dosing components, catalysts, and more, that monitors and interacts with each member of the network.

The ECM evaluates several parameters simultaneously, including:

• DEF quality

• DEF temperature

• DEF dosing accuracy

• NOx sensor readings

• SCR catalyst efficiency

• Overall NOx conversion performance

Because these systems depend on one another, a single failed component can trigger multiple diagnostic trouble codes.

For example:

• A failed NOx sensor may eventually lead to P220013, followed by P20EE00 because the ECM can no longer accurately evaluate SCR efficiency.

• Low-quality DEF may cause trouble code P207F00 or P207F9A. If low-quality DEF continues to be used, SCR Performance may degrade to the point trouble code P20EE00 is generated.

• A faulty DEF tank temperature sensor linked to P205B64 can improperly manage DEF, especially in cold weather, and can cause additional aftertreatment issues.

• Catalyst deterioration may initially show as P042000, but later on as NOx conversion efficiency continues to deteriorate, P20EE00 will result when the ECM detects that emissions are no longer meeting performance standards.

This is why replacing components based solely on a single stored fault code often leads to repeated repairs and recurring derates.

Diagnosis of the whole SCR and DEF system should be part of any complete assessment. This includes evaluation of NOx sensors, DEF quality, DEF dosing performance, catalyst efficiency, assessment of circuitry and ECM. The cost of a complete assessment is usually far less than the cost of multiple failed emissions component replacements if the root cause of the failure is identified later.

Why Do These Volvo D13 Fault Codes Keep Returning?

One of the biggest frustrations for truck owners is seeing the same fault code return shortly after repairs have been completed. In many cases, this happens because the stored DTC identifies only the symptom detected by the ECM—not necessarily the component that originally caused the problem.

Modern Volvo D13 engines perform round-the-clock monitoring of many systems with their turbocharger, fuel system and exhaust systems including EGR, SCR, DEF and NOx. Since these systems are highly integrated, even the simplest mechanical or electrical failure can cause multiple diagnostic trouble codes.

For example, the first indication of an aging NOx sensor may be a P220013. However, with poor emissions data, the ECM may conclude that SCR performance is no longer verifiable. In that case, the NOx sensor may also set P20EE00, P207F00, or P207F9A. The same is true for a simple boost leak where a P029900 may be set. However, if the boost pressure remains low, then prolonged operation will likely result in an increase in soot, worsening EGR and aftertreatment system issues.

Simply clearing fault codes or replacing parts based on the first stored DTC rarely resolves the underlying issue. The best repairs start with a thorough diagnostic evaluation that finds the primary cause instead of the first symptom that has occurred as reported by the ECM.

How DrunkLab Can Help

At DrunkLab, we specialize in Volvo engine diagnostics, ECU programming, emissions-system calibration, and advanced electronic troubleshooting. Our technicians are experienced with D13 engines, as they work on them every day and frequently identify issues with SCR, DEF, turbocharger control, EGR, fuel and engine electronics.

Using professional diagnostic equipment and years of practical experience, we help customers identify the actual source of recurring fault codes instead of replacing expensive components unnecessarily. Whether the issue involves intermittent electrical faults, aftertreatment performance, ECU software, or complex drivability problems, systematic diagnostics often reveal solutions that are not immediately obvious from the fault code alone.

Before owners conduct ECU programming or other emissions-related modifications, allowed in their jurisdictions, proper diagnostics should be completed. Addressing any existing issues with the vehicle’s systems first will increase the probability of stable engine performance.

FAQ

What is the most common Volvo D13 fault code?

There is no single "most common" fault code, but P20EE00, P029900, P205B64, P207F00, P207F9A, P040100, and P220013 consistently rank among the most frequently diagnosed Volvo D13 trouble codes. Most are related to the turbocharger or the emissions aftertreatment system.

Can I continue driving with these fault codes?

That depends on the specific code and its severity. Some faults may initially produce only a warning light, while others can quickly lead to progressive engine derates, reduced vehicle speed, increased fuel consumption, or further mechanical damage. Continuing to operate the truck without diagnosing the underlying problem is generally not recommended.

Can P205B64 cause an engine derate?

Certainly. The ECM depends on precise temperature readings of the DEF to control the SCR system. Therefore, an ineffective DEF tank temperature sensor and/or a problem with its circuit may result in SCR system faults and, in turn, cause progressive engine derate and/or emissions alerts, depending on the engine’s build, software version, and use conditions.

What is the difference between P20EE00 and P042000?

Both of these codes pertain to the aftertreatment system, however, these codes have their own unique functions.

P20EE00 references that the SCR NOx conversion efficiency has decreased and is no longer within the acceptable limits.

P042000 deals with overall catalyst efficiency. This could be caused by deterioration of the catalyst or issues with other aftertreatment performance.

Diagnosis will be complicated, as both codes will show the same symptoms, but the root cause will be different.

Can one problem trigger several Volvo D13 fault codes?

Yes. This is extremely common on modern Volvo engines.

For example:

• A failed NOx sensor may trigger P220013, followed by P20EE00.

• SCR efficiency faults may be caused by poor DEF quality which generates P207F00 or P207F9A.

• Turbocharger underboost (P029900) can produce more soot, which can then impact both EGR and aftertreatment indirectly.

For this reason, technicians should always diagnose the complete system instead of component replacement due to a single fault code.

Does replacing the NOx sensor always fix P20EE00?

No. Defective NOx sensors are one of the most prevalent causes of P20EE00. However, they are not the only cause. Before replacing parts, DEF quality, SCR catalyst condition, dosing performance, wiring integrity and even software calibration have to be checked.

Can poor DEF fluid cause multiple fault codes?

Yes, DEF fluid that is dirty, diluted or the wrong fluid can cause P207F00, P207F9A and as the SCR efficiency drops below threshold P20EE00 as well.

What should be checked first before replacing expensive emissions components?

Always begin with the basics:

• Read all active and inactive fault codes.

• Verify DEF quality.

• Examine electrical connectors and wiring

• Check NOx Sensor

• Confirm DEF Dosing Performance

• If there are boost-related faults, check the turbocharger and intake system.

• Confirm that fuel pressure and EGR operation are within specification.

A systematic approach to diagnostics is cost effective whereas replacing multiple emission components based on assumption is financially irresponsible.

Final Thoughts

D13 fault codes give insights on engine behavior. However, when diagnosing a problem, these codes should be used alongside other information. Modern Volvo engines utilize echoplex control systems. These systems integrate turbocharging, fuel injection, EGR, SCR, DEF, catalyst, and NOx. Each of these systems affect the others.

Understanding what a fault code actually represents—and what it does not—is the key to avoiding unnecessary repairs and reducing vehicle downtime. Accurate diagnostics when working with codes P029900, P20EE00, P205B64, P042000, P040100, P008700, P030000, P030100, P220013, P207F00, P207F9A, or others, should focus on the actual problem rather than guessing and replacing parts or clearing codes.

By having a more organized way of diagnosing issues, technicians can identify problems quicker, reduce costs on the repairs, allow the equipment to work properly again, and stop the previous fault codes from reappearing.

By Michael Carter

Independent Technical Writer

Last updated: August 06, 2026