W204 in limp mode.

[Hampstead]

It runs fine without the MAF sensors.

What’s the next step? Clean them?

 

[HITECH]

So nooo limp mode and full power? This is a really annoying complicated fault on the bigger engines bit simpler on the 2.2s. Not at home the now but that is progress In the right direction....

 

[Hampstead]

Yep. No limp mode and full power.

Thanks for your help by the way.

 

[HITECH]

OK now. Plug in sensor on left , lclear faults leaving sensor on right unplugged and run car for a day. If it starts going into limp mode same as before quite quickly then unplug the left sensor again and leave it out and plug the right one in. If it starts to do it again then unplug both sensors and run it like that and tell me the results.

Yep. No limp mode and full power.

Thanks for your help by the way.

 

[Hampstead]

Will do. I have a mechanic coming on Tuesday to fit a new blower fan. I’m going to ask him to clean the sensors while he’s here.

 

[Hampstead]

When you say left do you mean near side?

 

[Hampstead]

Right, so with either the left or right disconnected, it goes into limp mode.

 

[Hampstead]

I'm now running it with both MAF's disconnected and it's running fine.

 

[HITECH]

So that means when either of the MAF's are connected it will throw a limp mode fault. The chances of both of them going faulty at the same time are quite slim. But I'm not saying they cant be both faulty. It is just highly unlikely they are. See if you can keep running it with them unplugged. Then clear codes then see what codes come in running it like that for 2/3 days. Ignore the MAF fault codes as they will kick up just cause they are unplugged and it will not do the engine any harm at all running it like this . Only annoying thing is the EML light. Possibility are O2 sensors and a few other things. Im on nightshift next few nights so will have a think about it at work for a next trouble shooting step. For now run it as is with them disconnected. You should notice aswell it will not have that hesitation when u take off which it had when it was going into limp mode. When the mechanic fitted the blower fr you what was his imput on the fault?

 

[Hampstead]

The mechanic spent quite some time on the diagnostics. Whenever he was here, it was behaving itself. He saw the EGR code after I went for a spin at it started limping. He didn't really offer anything more than that.

 

[Hampstead]

Here the codes
P0112
P00AC
P0471

 

[HITECH]

Troubleshooting steps and what we done so far points to a faulty "exhaust back pressure sensor". I'll see if I can get a chance at work today to go thru the WIS and EPC see where they are on your engine. Keep running it the now with MAF's disconnected. Progress I'de say.......

 

[Hampstead]

It went into limp mode with both MAFs unplugged.
The code was P0112

 

[HITECH]

Keep clearing it for now. 112 is simply MAF disconnected alert. P0471 I reckon is the source of this fault right now. working out where them sensors are and changing 1 or 2 of them is next stepm

Replace exhaust back pressure sensor/s.

 

[OneForTheRoad]

Hi. Is this the MAF sensor?

View attachment 97757

Read post 10. The back pressure sensor is on the egr at the back, right side of the turbo. You can see it in the picture.