Mercedes Repair Questions? Ask a Mechanic for Answers ASAP
Hello, my name is ***** ***** I am a professional here at Just Answer. I have noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.The code P0120 can be set due to any of the following,
Okay then I will have to open the question back up for you as this is all the information I have. If someone has something different to offer, they will post back.
Hi, I've been following your post but haven't had time to reply. It looks to me like you have ruled out everything except the ECM. At this point I would either replace the ECM or send it to Beckmann Technologies for testing and repair. I've attached a link to their website below.
Let me know how you make out.
I've read through everything you have done and you've done a lot! It's time to send the ECU to Beckmann or swap it with another one. I wouldn't go through all of the trouble of swapping EEproms I would have Beckmann unlock a used one for you. I'm assuming that you have checked the battery and the alternator already. Overvoltage or undervoltage can cause the problem.
Good morning, in reading your posts it sounds like you have been very thorough in checking the wiring and you have already swapped the throttle body. You could try overlaying wires from the ECU to the throttle actuator to see if it still acts up. The connectors at the throttle body would be the most likely place to experience a wiring fault or high resistance. You could also try swapping the pedal value sensor but I don't see it causing this fault code. Aside from that there isn't much left other than the ECU.
Let me know how it turns out.
Hi, I can't see where tapping into the accessory wire would harm anything. I've never checked the 5V signal after shut off but I would expect it to go away with the key off. I'm not sure if that is normal or not but the 5V comes from the ECU so if it isn't normal I'd still say you have an ECU problem. If anything I would suspect that a bad throttle actuator damaged the ECU.