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P0631 is a diagnostic trouble code (DTC) for "VIN Not Programmed or Incompatible – TCM". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
A P0621 refers to the transmission control module's failure to recognize the vehicle's identification number.
The P0621 indicates that your vehicle's transmission control module has been unable to register its own identification number. Although this may be the result of faulty components, it's most often the cause of an improperly programmed command module.
If the vehicle's Powertrain Control Module (PCM) has been replaced, the connected modules will need to be reprogrammed accordingly. If this does not occur, it may result in a debilitating P0621 instance. If the PCM has been damaged or left unpowered for a long enough time, it may lose its memory and require programming. PCM and transmission control module-related wiring may also be a cause for this issue.
A P0621 trouble code will typically result in the vehicle's inability to start. Although it is a relatively simple and rare malfunction, the vehicle will be completely disabled until such a time where the problem has been solved. In any case, the vehicle computer will store a P0621 OBD-II code for diagnostic purposes and the dashboard light will be illuminated.
A mechanic may first diagnose the trouble code by hooking up an OBD-II code reader to the vehicle's onboard computer. All of the system-related wiring and connectors should be inspected thoroughly for signs of damage or corrosion.
If any modules require replacing in order to solve a P0621 code, they may require reprogramming after the fact. Besides that, due to the relative rarity and simplicity of the P0621, there have been few reported instances of misdiagnosing the issue.
Although a P0621 is usually simple to solve, the problem will likely result in the vehicle's failure to start.
The transmission control module and PCM will need to be reprogrammed by a mechanic in order to solve this issue. All wiring relating to the transmission control module should be checked for signs of trouble and react accordingly. After following through with any necessary repairs, make sure to give the vehicle a test drive directly afterwards to see if the trouble code returns.
The P0621 is noted for its rarity. Mechanics report few cases of this issue. The P0621 is usually avoided entirely by properly reprogramming modules in the first place.
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