Diagnostic trouble code (DTC) information

Condition 

The engine control module (ECM) contains a code for the immobilizer which is unique to each car. Before the engine can be started, the immobilizer code is checked to ensure that it corresponds to the central electronic module (CEM) and the engine control module (ECM). Diagnostic trouble code (DTC) ECM-720A, faulty signal, will be stored if the code for the immobilizer does not match.

Diagnostic trouble code (DTC) ECM-720A, signal missing, will be stored if there is no communication between the central electronic module (CEM) and the engine control module (ECM) so that the immobilizer code cannot be checked.

The fault is diagnosed by the engine control module (ECM) when the ignition is switched on.

Substitute Value 

none

Possible Source 

Faulty signal: 

• the engine control module (ECM) is not programmed and has no immobilizer code
• the immobilizer code in the engine control module (ECM) is incorrect
• the immobilizer code in the central electronic module (CEM) is incorrect
• the central electronic module (CEM) is not programmed and has no immobilizer code
• the central electronic module (CEM) is defective
• the engine control module (ECM) is defective.

Signal missing: 

• open-circuit in the communication between the central electronic module (CEM) and the engine control module (ECM).

Fault symptom[s] 

• the engine does not start.