EGR & Lambda DTCs

[A lex]

HiJack away

The more info gathered, the more useful it might be for others in the future

[A lex]

Nightmare.

Errors are back with a vengence.

MAF
Ho2S
Exhaust temp

plus an ECM to TCM error (but reading through the diagnosis list, this can be caused when the ECM cannot calculate the engine torque produced, which could (realistically) occur if one or more sensors are kaput.

Ive been and had a decent chat with the service manager at the dealership. He said they have seen a few cases where DPF problems/errors (like I had) have gone on to cause further problems with MAF fouling. So he was waging bets on it being the MAF, and that it is subsequently throwing other readings out.

When I clear the error codes and take a drive, I always seem to get the Ho2S error back before the MAF one, so im leaning toward it being the Ho2S.

Volvo want €360 for a MAF and €200+ for a Ho2S.

So I've just been online and ordered from Skandix. Original Bosch MAF and Skandix OE quality Ho2S for €330 delivered.

With the approaching roadtrip I cant afford to be messing around, so have ordered both. If this fix doesnt work, I have an appt next Tuesday at the dealer for a more thorough diagnosis (they have the ECM breakout boxes etc). If it isnt a sensor related problem, then im presuming it might be an ECM fault or a CAN wiring fault - which is bend over and receive time and also means I am up **** creek for the road trip.

Fingers crossed time!

[Funky Diver]

Originally Posted by A lex

Volvo want €360 for a MAF

OUCH!!

£22, but then I have no kind of warranty to worry aobut and it worked a treat.

Hope it sorts itself out by the time of your road trip

[A lex]

Gah. Hasnt worked

New MAF and Ho2S installed and parameters reset.

Drove 5km and it was back. Same codes:

MAF signal too low
Ho2S signal too low
ECM to TCM comm failure.

[Funky Diver]

Have you been able to communicate with the ECM via DICE or is it completely jiggered?

[A lex]

Everything works fine via VIDA. Can interrogate and monitor without issue.

[A lex]

Looking through the VIDA fault finding list, it seems the boost-pressure sensor can cause hiccups with the MAF.

This would also tie-in with when the problem seems to arise (full throttle application in a high gear from low speed - i.e. max boost).

Im not going to do anything about this, but I will mention it to the Volvo dealer when the car goes in on Tuesday.

[cheshired5]

Originally Posted by A lex

Ive been and had a decent chat with the service manager at the dealership. He said they have seen a few cases where DPF problems/errors (like I had) have gone on to cause further problems with MAF fouling. So he was waging bets on it being the MAF, and that it is subsequently throwing other readings out.

I'd be interested to know how egr gases can make their way in reverse and through a spinning turbo to foul a MAF.
I think you've been fed a very expensive bit of guff.
A MAF is a sensor and like any sensor, it can and should be tested before condemning......... unless they're the ones paying for the bad guesses.

[A lex]

Originally Posted by cheshired5

I'd be interested to know how egr gases can make their way in reverse and through a spinning turbo to foul a MAF.
I think you've been fed a very expensive bit of guff.
A MAF is a sensor and like any sensor, it can and should be tested before condemning......... unless they're the ones paying for the bad guesses.

Yup, theres obviously a certain amount of guff to wade through.

I wasnt interested in replacing it at Volvo prices, but for what I paid I think it was a reasonable gamble.

At least now I can firmly tick off the MAF as being OK. Perhaps one step closer to the solution.

[cheshired5]

Originally Posted by A lex

Yup, theres obviously a certain amount of guff to wade through.

I wasnt interested in replacing it at Volvo prices, but for what I paid I think it was a reasonable gamble.

At least now I can firmly tick off the MAF as being OK. Perhaps one step closer to the solution.

True, you can eliminate that.
I would suggest to anyone to buy a used genuine MAF just to have in a drawer as a back up.
They're easy to test as working and can be picked up for next to nothing. My last was £15.
Good luck with the ongoing diagnoses.