Immobilizer Key Not Programmed – ECM/PCM


The immobilizer key is not recognized by the PCM.

Code Set Parameters

If the PCM fails to recognize the immobilizer key, due to a lack of proper programming or other internal malfunction, a code will be stored and a malfunction indicator lamp will be illuminated.


It is very likely that if the PCM fails to recognize the immobilizer key, a no start condition will also be exhibited. A “Security” lamp may also be illuminated.

Common Causes

The most common cause of this code being stored is that the PCM has been replaced and not reprogrammed to match the vehicle. The only other possible causes are a faulty PCM, shorted or open wiring or connectors, a defective ignition cylinder, or a bad immobilizer key. If the battery becomes discharged and the PCM is deprived of voltage for a long period of time, it may need to be reprogrammed. The period of time required for the PCM to completely lose memory varies from one manufacturer to another.

Common Misdiagnosis

As these types of malfunction are rare, and possible causes are very limited, there are few rational misdiagnosis’ to report.


  • Several tools will be instrumental in attempting to successfully diagnose this code
  • A suitable OBD-II scanner (or code reader) and a digital volt/ohmmeter will be most helpful in trying to perform a successful diagnosis
  • Begin with a visual inspection of all wiring and connectors
  • Repair or replace damaged, disconnected, shorted, or corroded wiring, connectors, and components as necessary
  • Always retest the system after repairs are completed to ensure success. If all system wiring, connectors, and components (Including fuses) appear to be in normal working order, connect the scanner (or code reader) to the diagnostic connector and record all stored codes and freeze frame data
  • This information can be extremely helpful in diagnosing intermittent conditions that may have contributed to this code being stored
  • Continue by clearing the code and operating the vehicle to see if it returns
  • This will help to determine whether or not the malfunction is intermittent
  • After the codes are cleared, test drive the vehicle to see if the code returns
  • If the code fails to immediately return, you may have an intermittent condition
  • Intermittent conditions can prove to be quite a challenge to diagnose and in extreme cases may have to be allowed to worsen before a correct diagnosis can even be attempted
  • Modern OBD-II systems are programmed to function in only one individual vehicle
  • The vehicle’s pertinent data is programmed into the PCM, and then shared with all of the other control modules via the CAN bus network
  • The days of replacing a PCM, or other control module, with a used component and driving away are over
  • If a control module is replaced, it will need to be reprogrammed to match the vehicle
  • The vehicle type, identification number, mileage, and antitheft settings are all included in the process of reprogramming the control module in question. Diagnosing the cause of this code can prove to be impossible without the use of a specialized scanner or an Autohex
  • If recent repairs have included control module replacement, suspect a reprogramming problem. You may use an auxiliary immobilizer key to test the key’s validity
  • Some vehicles have also had a history of defective ignition cylinders.