W204 P2122 Code

[RM88]

Good Morning,

Driving to work today I noticed that the throttle input felt a little different. About half way through the trip had a warning that ESP and TPS was inoperable and the throttle input was virtually none existent while pulling off but did improve as the revs got up. Managed to get to work and scan it with my OBD reader. It's showing P2122 (Throttle Position Sensor/ Switch D Circuit Low).

Doing some googling it obviously relating to the throttle position sensor but has anyone had any experience of this and the best place to start. I understand it can be the sensor itself or wiring etc so any help would be appreciated as this does seem to need a bit fault tracing to find the cause. As a side note I cleared the code and throttle input was back to normal but want to fix for obvious reasons.

Many Thanks

Car is W204 C200 CDI

 

[BlackC55]

It will probably be a throttle pedal issue or the wiring to it. Fault codes are only 50% of the info you need. Live data will help in this.

 

[RM88]

Thanks BlackC55, appreciate the response. I took a punt on a second hand pedal hoping it would be the easy fix. Unfortunately the code and fault is still there. It also occurs with just the ignition on if I fully press the pedal. A quick off and on and it’s fully drivable again. Would this point to a sensor rather than wiring?

What live data should I be looking at? Thanks

 

[BlackC55]

Throttle pedal position data needs to be smooth and consistent.

 

[RM88]

Just an update for anyone interested or comes across this problem themselves. It turned out to be the auxiliary battery in the boot. The car actually broke down dropping my son to school. Engine light on and a load of codes some relating to internal control modules. I had already tested the main battery and was fine, however when checking the aux battery it was showing 7.5v! so completely dead. What is interesting is the car never gave me a warning of this. Anyway new aux battery and the car has been faultless for the last 4 days whereas prior to this the problem of limited power and P2122 warning would happen multiple times a day. I can only assume that the dead aux battery was putting more pressure on the main one, leading to poor voltage delivery the control modules and sensors.

Thanks BlackC55 for responding and sharing your knowledge.