I have a good one for you guys. 2003 Mercedes e320. I reset my transmission shift points. Afterwards I hooked up scanner and had pending p0123. It doesn't throw a check engine light and pending code goes away after a couple days. If car is running and you floor it and activate kick down it doesn't happen. It will only happen when car isnt running and in on position. My friend has the same car and it doesn't do it in his. The car does have a minor misfire and vibration which is little worse in drive. There also is a hesitation which only happens under moderate to heavy acceleration. Do you guys think the pedal position sensor is starting to go. Maybe it's the throttle body . I'm curious what you think. I personally think it's the pedal assembly starting to go.
I don’t know Mercedes’ specifically but most manufacturers if there is a misfire at all it won’t allow certain performance abilities in order to try and save the power train and converters. If you do in fact have a misfire that is most likely your hesitation and I would address that first
As far as I know, on a Benz, you normally only get P0123 when one of the following 2 conditions occurs:
when your throttle position sensor, which is sitting on your throttle valve, and which is supposed to be delivering voltages ranging from 0.3 (0.6) V (= throttle closed) to approximately 4.5 - 4.7 V, at least sporadically delivers voltages exceeding 4.8 V (could be due to a faulty sensor, a faulty ECU, or a wiring short circuit);
or
if this sensor circuit´s connection to the ground (to the negative, to the vehicle chassis) is not OK.
This code has nothing to do with pedal position.
Both conditions can be easily checked using any cheap multi-meter. Often this is just bad contact in the sensor connector.
How to check>
Turn ignition on
Disconnect the throttle connector
Measure the voltage between the C contact of the disconnected harness connector and the negative battery terminal:
less than 1 V = sensor gets no power from the ECU = wire breakage or faulty connector
more than 10 V = short circuit in the harness or faulty ECU
about 5 V = sensor gets adequate power from the ECU, proceed to measuring another contact:
measure electrical connectivity between the B contact of the disconnected harness connector and the positive battery terminal.
If connectivity is present, most probably your sensor is dead. If it is not present, you either have a broken wire somewhere, or your ECU is faulty.
It just weird that it will throw a pending code only if car is not running and in on position. I feel the very minor misfire and vibration is caused by a leaky/faulty fuel injector. Other then what's listed the car drives great, no performance lose at all.
Once weather gets better I'll check it out.