If you receive the ECU back and for some reason isn’t starting now, ask yourself the following:
- Was it starting before? Might be another issue
- Is this the original ECU
- If not, did you get one with matching part no.?
If you replaced ECU it must have the exact part no. otherwise it won’t work and sometimes even then the immobilizer needs to be cleared so that the vehicle can accept the new ECU
Also, if the car is not starting when did this happen (after our service or it was never starting before because if it wasn’t starting before that might be an indicator that the problem may lie somewhere else) It could be in engine safe-mode the only way to determine is to proceed with the steps below that you can try in the car.