OBD-II DTC Technical Description
Error in Internal Control Module Read Only Memory (ROM)
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to OBD-II equipped vehicles. Although generic, the specific repair steps may vary depending on make/model.
This trouble code essentially indicates that the PCM/ECM (powertrain/engine control module) has detected a fault in the ROM (read only memory) of the internal control module in the PCM. The PCM is essentially the vehicle’s “electronic brain” that controls functions such as fuel injection, ignition, etc. When self-checks fail in the ROM, this DTC is triggered.
This code is a generic powertrain code. It is considered generic because it applies to all makes and models of vehicles (1996-newer), although specific repair steps may be slightly different depending on the model. A cursory search on the internet shows this DTC to be more commonly found in Ford and Nissan vehicles.
Other trouble codes related to internal control module errors include:
Photo of a PCM with the cover removed:
Symptoms
Symptoms of a P0605 DTC will include the illumination of the MIL (malfunction indicator lamp), although there may be other symptoms including but not limited to various warning lights on the dashboard, stalling, and no start conditions.
Potential Causes
Possible Solutions
In some cases, updating the PCM with new software can resolve this DTC. You will need access to make and model specific information such as Technical Service Bulletins (TSBs).
If there are no PCM flash updates available, the next step would be to check the wiring. Inspect and check for proper voltage and ground to the PCM and throughout the associated circuits. If there are any issues, repair and retest.
If the wiring checks out OK, the next step is to replace the PCM, which is the most likely repair for this code. This is generally not a DIY task, although in some cases it may be. We strongly recommend having a qualified repair shop or technician perform the work, one that has the capability to reprogram the new PCM. Installing the new PCM may involve using special tools to program the vehicle’s VIN (vehicle identification number) and/or anti-theft information (PATS, etc.).
As an alternative to replacing the PCM, some specialized shops may be able to repair the PCM. This may involve removing the PCM, sending it off for repair, and reinstalling it. However, this option may not be available for daily drivers.
NOTE: This repair may be covered under the emissions warranty, so be sure to check with your dealer as it may be covered beyond the bumper-to-bumper or powertrain warranty period.
Other PCM DTC codes: P0600, P0601, P0602, P0603, P0604, P0606, P0607, P0608, P0609, P0610.
