Fault code P0631 is called “VIN Not Programmed or Incompatible – TCM” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.
Technical description and explained code P0631
Stored code P0631 means that the control module (TCM) does not recognize the 17-digit vehicle identification number (VIN). Other controllers may also detect an incompatibility error (VIN) and cause this code to be stored.
Every vehicle manufactured in the world today is assigned an identification number (VIN). It consists of a series of numbers and letters that indicate the country of manufacture, year of manufacture, make and model of the vehicle.
Any special equipment, engine size and type may also be specified. The last six digits at the end of the VIN indicate the sequence in which each vehicle was manufactured.
The VIN number is the individual number of any vehicle, which will be different for each vehicle.
System controllers cannot be interchanged between vehicles unless they are programmed for the respective vehicle. When the ECM/PCM is replaced, the odometer reading and vehicle VIN must be programmed into it.
If the TCM cannot find or recognize the VIN, code P0631 will be stored and the Malfunction Indicator Light (MIL) may illuminate. The TCM compares the VIN number when the key is turned on and performing a self-diagnosis. In most cases the TCM will not operate without the correct VIN recognition.
Symptoms of vehicle malfunctions
The main signal that an error P0631 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.
It can also be warning signs such as:
- The “Check engine” control lamp on the control panel will light up (the code will be stored as a fault).
- Other related fault codes may also be present.
- The engine will not start.
- Activation of the vehicle’s safety system.
The stored fault code P0631 should be categorized as serious, as the TCM is unlikely to operate without VIN recognition.
Factors that can cause this error code
The error code P0631 can mean that one or more of the following problems have occurred:
- TCM programming error.
- Replacement of TCM from another car without proper programming.
- Sometimes the cause is the TCM module itself.
How to fix or reset OBD-2 code P0631
Some suggested steps for troubleshooting and fix the error code P0631:
- Read all stored data and error codes with an OBD-II scan tool. To find out when and under what circumstances error P0631 appeared.
- Use the scan tool to read the vehicle VIN and see how it is perceived by the TCM.
- If the VIN is not displayed, you must look for a problem with the TCM.
Diagnose and repair of problems
Unlike most other stored codes, P0631 is usually associated with a TCM malfunction or programming error. Without the ability to properly reprogram the controller, successful repair will be unlikely.
Diagnosing this code will require a diagnostic scanner and a source of vehicle information. You will need to connect the scan tool to the vehicle’s diagnostic port, read the VIN and see how it is perceived by the TCM.
Compare the VIN on the diagnostic scanner to the actual VIN, usually at the bottom of the windshield on the driver’s side. If the VIN tag does not match the number displayed on the scan tool, the TCM was most likely supplied from another vehicle.
If the VIN does not show up on the scan tool, then the TCM was replaced without programming to match that vehicle. If this is not the case, a TCM failure or programming error may have occurred.
The main problem with the occurrence of error P0631 is the replacement of the controller without proper programming and adaptation to the specific vehicle.
On which vehicles does this problem occur most frequently
Fault code P0631 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:
Fault code P0631 can sometimes be found with other errors. The most common are the following: P0630, P0632, P0633.