What does it mean?
P1679 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Control Module Not Added .
Symptoms
- MIL on, often with warning lamps or fault codes in several other modules
- Functions of the newly fitted or replaced module do not work although it is wired correctly
- Scan tool lists the module as not coded or not installed
- Multiple communication codes appear across the network
- The code returns immediately after clearing, with no mechanical symptom at all
Likely causes
- A module fitted or replaced without being entered in the gateway installation list
- Retrofit or optional equipment installed and wired but never coded into the vehicle configuration
- Coding session that was started and not completed
- Gateway module replaced or reset, so the stored vehicle configuration was lost
- A used module from another vehicle carrying the wrong configuration data
- Programming interrupted by low system voltage
- The module is unreachable on the bus, so the vehicle records it as not installed
How to fix it
- Read the gateway installation/configuration list and compare it with the modules actually fitted to the vehicle
- Identify which module was recently replaced, retrofitted or removed
- Connect a battery support unit so voltage stays stable throughout the coding work
- Add the module to the installation list and perform the required coding and adaptation with a capable tool
- Verify that the hardware and software part numbers match the vehicle's equipment level
- If the module cannot be reached at all, check its fuse, power, ground and CAN wiring before attempting coding
- Clear all fault memories afterwards and re-scan every module to confirm the network is complete