ECU reset

[Jimmyboy]

Not a very original subject I'm afraid!! Does anyone know the facts about resetting the ECU? I have a C220 CDi diesel.

(a) When my car goes into limp mode ( I THINK it is limp mode), if I switch off the engine and restart it, limp mode seems to disappear for a while.

(b) The handbook says if you turn the steering wheel lock to lock this will reset the ECU warning light. I have never had the warning light come on but how on earth can turning the steering wheel reset the electronics in any way?

(c) If a non-digital sensor like the MAF or the MAP fail, and signal the failure to the ECU, when the part is replaced does the ECU have to be reset (by a star machine or otherwise) in order to 'forget' the previous failure?

Any info on these points????

 

[Cole@MBS]

Barking up the wrong tree!!

By turning the steering wheel, your setting the zero point on the steering angle sensor, thats controlled by the esp control module!

Its has little to do with the engine control module apart from comms

Wait until thursday Jimmyboy and we will tell you/show you whats wrong!!

 

[Jimmyboy]

OK thanks S-A-M / U-N-I-T. Thought you would see it!!!!!! I'll wait till Thursday for the facts.

 

[jberks]

(a) When my car goes into limp mode ( I THINK it is limp mode), if I switch off the engine and restart it, limp mode seems to disappear for a while.

A restart will switch off limp mode every time. It will come back when it re-detects the fault.


(b) The handbook says if you turn the steering wheel lock to lock this will reset the ECU warning light. I have never had the warning light come on but how on earth can turning the steering wheel reset the electronics in any way?

As above - it resets the ESP warning light after you've reconnected the battery.

(c) If a non-digital sensor like the MAF or the MAP fail, and signal the failure to the ECU, when the part is replaced does the ECU have to be reset (by a star machine or otherwise) in order to 'forget' the previous failure?

The code may be retained in the history but thats not an issue. The car will run properly without any star intervention (see a).

 

[nickcc101]

If the engine management light has been triggered then you will need to remove the fault code, after replacing the faulty part, or the warning light stays illuminated. I found this to be the case after changing one of my O2 sensors and carried out the reset using a cheapo scanner/reader.