Wiggis

Hi all! I've got a 2012 C63 AMG with around 30k miles on it. Drives well, pulls like a train, no lights on the dash.

However ... I noticed that when idling, every now and then, there is a very slight kick that you can feel through the pedal. Like a very subtle misfire. So I connected up an ELM327 fault code reader, and the Torque app shows three logged faults - all of which are grey, so might not be active.

P0866, P1106 and P374A

These seem (from what I've read) to point towards the MAP sensor having some kind of problem.

Any experts here who could tell me what to look at?

Mort

I did not check the codes but this is the first issue I have seen about the MAP sensor. Check all the vacuum lines, especially those around the front of the engine. Look for split or worn looking lines or suspicious connections. A small leak might cause a slight lean condition leading to a bit of a stumble without enough to set a lean code.

Wiggis

Thanks Mort - I just did exactly what you suggested, found no odd looking vacuum pipes, but I also took off and re-seated the MAP sensor connector.

Then I went and filled up with gas - and guess what - the problem didn't happen, plus the car felt stupidly quick (more than normal)

I'm still curious what the codes actually mean, if anyone has a way to look them up? they seem MB specific and a general search didn't turn up anything useful.

Jasonoff

You try searching on here?

Below was a drivetrain issue (P374A) caused by a paddle shifter connection. Your P0866 TCU issue could be related.
https://mbworld.org/forums/c63-amg-w...n-problem.html

Wiggis

Yeah, I did take a look, and noticed that thread. I haven't actually used the paddle shifters since I got the car! Happy with C, S and S+ modes so far... LOL

Wiggis

So I have a new code in addition to the original 3. P0651. Any clues?

Jasonoff

https://mbworld.org/forums/c-class-w...7-request.html

P0651 - B37 (Accelerator pedal sensor) : Power supply

Whatever TF that means. You have some weird shìt going on man. Get the bìtch scanned.

jptaylor

So, if you have Torque Pro(pay for the app people) then when you scan the codes it will allow you to touch any shown code and give you a Web Lookup option....will tell you more than enough

Wiggis

I do have the paid-for Torque Pro. Sadly, it doesn't have anything useful to say on the codes logged - not even on the web lookup - the only one it says anything about is P1106, when it serves up a red herring about the MAP sensor...


However ... after a lot of digging around, I did find out what these codes all meant for the specific M156 ME 9.7 AMG ECU. And I learned that these are all 'pending' codes, and therefore there is no freeze frame data.


P0651 - B37 (Accelerator pedal sensor) : Power supply low.
P0866 Power structural assembly engine control unit / Low battery voltage.
P1106 Relay 'terminal 87' (engine) (P2505) voltage low.
P374A Failed to save the internal data in the control unit.


The probable answer? well the battery was sitting at 10.9v right before cranking the engine. And they all seem related to voltage being too low. The car just hadn't been driven enough, and I *might* need a new battery at some point


I'm not sure about P374A - could be related to the paddle shifters - but I don't have a actual fault, so I'm happy.

Jasonoff

Replace battery (if you need to), erase codes, /thread