see_sicky_tree

I have a P0638 code and my car is in limp mode and will not get out of it even if i restart the ecu. I already tried replacing the accelerator pedal, but that did nothing. Is there a sensor in the throttle bodies? Is there one or two? Thanks!

Plutoe

Nope you wasted your time and money, sell the car or replace the throttle body!!

see_sicky_tree

Not sure if being sarcastic...

Plutoe

Not at all, it's just that most used MB owners can't believe the expenses associated with the repairs, plus their girlfriend at a local garage doesn't have the knowledge or tools to quickly diagnose the problem---then they drift to the forums and are bombarded with all sorts of misinformation----then they start changing the wrong parts------and so far the car has not been diagnosed properly with loads of unnecessary expenses---my point get the car diagnosed first before you do anything and yes that cost money!!

PS: There is no mindmeld method to freely diagnose cars!!

beejAMG

its Plutoe, always assume that he is being sarcastic. but he might be right with the throttle body.

iShootYou

Its probably your throttle bodies, well the sensor in the tb not the tb itself, tps issues are rarely ever the pedal. I don't know how the sensor are attached to the tb so it may or may not be a part you can just replace...I will look into this for you.

jay rick

So what exactly happened?
I had a tps sensor pop a few times, it disable the traction control and turns the car into limp mode. If i restart the car it will go away.
But if it happened consiquetly it will pop the engine light.
My mechanic told is the tps and order the pedal. Still waiting for it.

tdpthagenius

Jayrick do you have an update for us? My car is doing the exact same thing right now...

604 C63

Thats like saying "my electric guitar isn't sounding right, but Im hoping if I get a new pick......"

Merc63

I bet you have something stuck in the throttle body on bank 1. Take the intake manifold off to access the TBs inside it.

If you hook the car up to the computer and check the voltage on the throttles. They should both move identically. If one stops, it's blocked physically or broken.

Once had this happen, took it apart and a piece of the air filter was caught in the throttle plate.

mr747

this same problem keeps popping up

Seeems to be a common problem

I purchased some new throttle bodies and my problem is gone

Merc63

Well it just an electric motor that turns the plate, they are right in the intake and it's probably really hot in there.

jay rick

I got the pedal replaced and the problem is gone.

Celicasaur

This is an interesting thread. Seems like throttle issues are becoming more and more commonplace on the M156.

My car doesn't seem to be in limp mode, but I do wonder/hope the new throttle bodies will cure the power drop. I'll be sure to post up results if and when they do.

tdpthagenius

thanks Jay...where did you order your pedal from?

C63Dave

Hello fellow m156 drivers, just wanted to share my experience to hopefully add value to the next driver down the line....

I had a P0222 Throttle/Pedal Position Sensor/Switch B Circuit Low code come on after I had removed my intake manifold to replace the PCV and add a catch can. I jumped to the forums to see if anyone had the same issue and one found a few people experiencing similar problems...

The consensus was to first get it properly diagnosed, but a few drivers installed new accelerator pedals or throttle bodies and had success.

Since I was really trying to do all my own maintenance I figured I could at least test the accelerator pedal theory by purchasing one (used $70 from ebay) and see if that made a difference.... Installed and welp... no difference.

Fearing I may have to replace/upgrade the TB, I stopped by my local indie shop to get hooked up to the STAR machine.... The reading was able to show there was a fault to ground one of the 4 plugs on the intake manifold. After removing the second or third plug we found an electrical pin had been bent when I pushed the plug together...

The tech straightened out the pin, and I earned the title at the shop of "hack of the day" haha.... fair enough.

After replacing spark plugs, fuel injectors, removing the intake manifold, replacing a PCV valve and adding a catch can as a DIY MB World and YouTube mechanic, I am really happy that a bent pin was my only issue.

Long story short, check the pins on electrical plugs on the front of the manifold before buying parts or causing a few laughs at your local shop!

-C63Dave

lewissmith_28

Hi please can someone advise after going into limp mode, Diognostic gives these two faults

“position sensor 2 for throttle valve two has a short circuit to ground”
”the values from the c/g position sensors of throttle valve are implausible in relation to one another”

both throttle flap/valves (A2761410125) seem to all be functioning fine? Is there more throttle sensor I need to be looking for?

66plate Mercedes Benz c63s