W204 2012 220CDI - Gas Pedal Stops working whilst driving! Please HELP me :(

[220problem]

From my other post:
I have recently started to experience some issues with my w204 C220 - 140K on the clock (motorway mileage)

Over the year I have had, DPF cleaned, DPF sensor, new EGR Valve, transmission mount, and transmission oil change and most recently new water pump which has been great for the past 10k miles and now the latest new thermostat housing.
9 months ago I had a new throttle body replacement as well.
new Thermostat fixed itself whilst driving, holds for longer around 85 - 90 degrees

I have spent a fortune and if someone can help me please, I am now spending all my wages on my car. I would change my car if I could afford to but I have no other option at the moment to only keep this car.

Now my new problem has become a safety issue for me and others driving around me.

I am driving on the motorway or dual carriage way, and my accelerator stops responding, it completely stops and then I try coast to the hard shoulder and stop my car, restart it and it is all fine.

I usually do not drive with Eco stop/start on, do you think this will help me when I come to a stop the engine will start again and help me along?

But this danger to me and others around me is so worrying. And on the other hand I have fixed so many issues over the last two years with my car that I can't believe all these errors are occurring every time something gets fixed.

Codes that I do get when i plug in the icarsoft mb v3 which is these;

W204 p0123 throttle / pedal position sensor switch a circuit high (I replaced the pedal around 8 months ago)

P2015 - Intake manifold runner position sensor/switch circuit range/ performance bank 1

P2112 - Pending throttle actuator A control system - stuck closed

Can someone help, its problem after problem and I have had the car on Star and it always passes the checks - I get the problems mainly driving on dual carriage way and motorway between 50 - 70mph i try drive by the hard should now

 

[Corty]

I can sympathise with you, I bought my 140000 mile w204 six months ago and it has been one thing after another with this. If I don't get my current problem fixed I will just throw in the towel with the car. Good luck with yours, I hope you get a fix for your car.

 

[mioba]

The car is simply at a mileage where things wear out and need changing.

it is strange STAR picks nothing but ICARSOFT does. cNt b true - are you interrogating correct modules.

seems like a pedal sensor - dis you replace with genuine or aftermarket - mercs hate aftermarket eleteics

 

[Corty]

Yes I agree, my Icarsoft says that the egr cooler bypass y85 is faulty yet nothing was found when put on star.

 

[220problem]

Let me make it more clear

The codes on icarsoft are stored codes. When I restart my engine then the codes are all gone and looks like it goes into stored on the icarsoft. Remember this only happens when I am driving on the motorway or dual carriage the pedal cuts out.

When plugged in Star this is when i am at the garage my mechanic will plug it in whilst the car is stationary and all the "stored" codes come up, he has tested the problems and they all get green ticks on Star.

The other technical parts I do not know. The pedal is from Mercedes it costed me £159.

 

[220problem]

I can sympathise with you, I bought my 140000 mile w204 six months ago and it has been one thing after another with this. If I don't get my current problem fixed I will just throw in the towel with the car. Good luck with yours, I hope you get a fix for your car.

I hope your car works out as well. Literally savings and wages gone in this mercedes
If you have the option throw the towel in for another Mercedes with less mileage

 

[mioba]

Your mechanic needs to take the car on the motorway and get live data

 

[mioba]

if he is just testing a stationary car, despite what you told him and saying everything is fine - then he is not the best imho

 

[220problem]

Yes I agree he did take my car for a test drive when the thermostat had problems, but then this weekend I think he will drive the car and check out the pedal issue. please don't grill me, i'm asking simply if anyone has had this type of issue what resolved the issue, or what can cause it. I'm just looking for help, i'm trying to do the right thing here.

 

[colinallcars]

Had a similar issue with our SLK, the problem was the throttle body

 

[leef44]

Had a similar issue with our SLK, the problem was the throttle body

Can you elaborate, what was the cause of the failure of the throttle body?
Was it high mileage?
I take it your one is not diesel?

 

[Petrol Pete]

OP , not wanting to rub it in but have you had the rear subframe inspected on this car ? If not then get it done before you spend any more money on it.

I can't help with your throttle problem but best of luck .

 

[220problem]

Can you elaborate, what was the cause of the failure of the throttle body?
Was it high mileage?

OP , not wanting to rub it in but have you had the rear subframe inspected on this car ? If not then get it done before you spend any more money on it.

I can't help with your throttle problem but best of luck .

Thanks i'll check the rear sub frame out. The latest my mechanic thinks is the ECU wiring is causing a problem because it is throwing a lot of errors, but when I drop the car in, i'll mention what you said.

 

[colinallcars]

Can you elaborate, what was the cause of the failure of the throttle body?
Was it high mileage?
I take it your one is not diesel?

Not diesel but, as I understand it, the same fly by wire principle - the movement of the throttle pedal is transmitted via a potentiometer to a second potentiometer in the throttle body. In my case it was this second potentiometer that had failed at 110K miles. Got one from ebay for £25

 

[220problem]

Not diesel but, as I understand it, the same fly by wire principle - the movement of the throttle pedal is transmitted via a potentiometer to a second potentiometer in the throttle body. In my case it was this second potentiometer that had failed at 110K miles. Got one from ebay for £25

Nice... glad that worked for you, sounds promising, do you know if Star can pick this up or test this part?

Also have you got a link to the part, at the moment it's worth me trying anything and everything.

 

[colinallcars]

Nice... glad that worked for you, sounds promising, do you know if Star can pick this up or test this part?

Also have you got a link to the part, at the moment it's worth me trying anything and everything.

I used iCarsoft. The fault code was similar to yours, throttle position sensor which I interpreted as throttle body.
It will be a different part number for yours, look it up on one of the online Parts catalogues.

 

[220problem]

Just to update you all - the main problem is the wiring harness going to the ECU socket with the clip. This was coming loose due to the ECU erratically shaking, two grommets needed replacing and now the ECU doesn't shake and the connection stays in the ECU socket. So a lot of these errors seem to be caused by this. I've now done 150 miles and the car was solid no issues. Thank you all for your suggestions and solutions.

 

[DrNick]

Just to update you all - the main problem is the wiring harness going to the ECU socket with the clip. This was coming loose due to the ECU erratically shaking, two grommets needed replacing and now the ECU doesn't shake and the connection stays in the ECU socket. So a lot of these errors seem to be caused by this. I've now done 150 miles and the car was solid no issues. Thank you all for your suggestions and solutions.

How did this get identified? Just by luck or did someone get some inspiration or just get desperate?

 

[220problem]

What do you mean "just get desperate"?

 

[220problem]

Common problem on w204 is wiring harness issues. After reading forums and articles and understanding my problems. My mechanic wanted to check the ECU, ingress and test the wiring looms, check and so on.

Once this was all checked, as mentioned my long trip had no issues, better performance and surprising the heating felt better. New tape added to the looms, you can buy it from Mercedes parts store.

As always to anyone reading this, use original Mercedes parts.