Information About Permanent Diagnostic Trouble Codes

NOTE: This service only applies to vehicles the USA and Canada, for model year 2010 and later, and only in certain versions.

Problems that impact emissions, and that are found by the control module's diagnostic system, from model year 2010, generate extra diagnostic trouble codes in parallel with the traditional diagnostic trouble codes. The diagnostic trouble codes are called permanent diagnostic trouble codes, stored in a separate diagnostic trouble code memory and have the same designation as the traditional diagnostic trouble codes.

The difference between the permanent and the traditional diagnostic trouble codes is that the permanent cannot be erased with an external diagnostics tool, e. g., VIDA (Volvo scan tool). The permanent diagnostic trouble codes in the control module are erased automatically when the diagnostic system has performed relevant diagnoses, and ensured that there no longer are any emission-related malfunctions in the system.

The purpose of introducing permanent diagnostic trouble codes is to meet a government regulation. By this requirement you prevent that emission-related problems with their diagnostic trouble codes can be hidden temporarily, e. g., at an inspection, by only erasing diagnostic trouble codes and this also turning off the MIL-light.

Emission-related diagnoses are available in Engine control module (ECM) and in Transmission control module (TCM), and thus you can only find permanent diagnostic trouble codes in these two control modules.

Perform the following procedure in this order to ensure that emission-related problems have been solved correctly and that the diagnostics system is free from diagnostic trouble codes.

Troubleshoot and solve and problems acc. to traditional procedure.
Erase diagnostic trouble codes (DTCs).
NOTE: This erases the traditional trouble code memory and turns off the MIL-light. However, the permanent diagnostic trouble code remains.
Make sure that the control module's diagnostic system can run the diagnosis/diagnoses again for relevant diagnostic trouble code.
HINT: The requirements for running a diagnosis may vary between different diagnoses. Certain diagnoses only require ignition position II, while others require that the vehicle is driven on road acc. to a specific driving procedure. For detailed information on what is required for a certain diagnosis, see Diagnostic trouble code information for each trouble code.

Before the permanent diagnostic trouble code disappears from the diagnostic trouble code memory, the vehicle must have undergone a so-called simplified general drive cycle. This means the following:

Engine idling for at least 2 minutes.
Vehicle speed over 40 km/h (25 mph) for at least 5 minutes.
Total time with engine on for at least 10 minutes.

NOTE: The above conditions also apply to diagnoses with simpler running conditions.

When the diagnosis has been run, the diagnostic system has either assessed the system as:

Trouble-free.
The permanent diagnostic trouble code is now erased. The vehicle is ready for delivery to customer.
Incorrect.
The permanent diagnostic trouble code remains. The traditional diagnostic trouble code is stored again. After another diagnosis has been run with problems, the MIL-light will turn on, however, first in the next driving cycle.

Continue
Refer to READING OUT PERMANENT DIAGNOSTIC TROUBLE CODES (USA/CDN)