pdt6974

Several months back I got an error indication a malfunction with TPMS, Hill Assist, ACC, Suspension Level Control. Took it to the dealer who said it was the battery controller. They replaced controller and the problem went away...until now. Now it is reoccurring almost daily. The engines becomes unstable and eventually it will throw a P0106 code. I replaced the mass air/barometric pressure sensor (see picture, black and green wire leading in) but the problem has not resolved. I haven't really figured out a pattern yet but wanted to check here to see if anyone has had a similar problem.

MP4.2+6.0

If P0106 = really basic generic code scan tool like I suspect, not good enough.

Get a thorough scan with VCDS or shop equivalent of ALL modules, not just OBDII codes that a cheap code reader does. You want to look and see what codes are in all the modules you mention, power management (battery) module, anything else in engine, any other modules, etc. All OBDII code readers do are see generic codes in the ECU, not the dozens of other modules the car has and a good tool is capable of reading for diagnostics.

Without that we are all just guessing and you are throwing $$ and parts at it. Could be most anything right now from recurrence of prior issue, to failing battery, to wiring, to who knows. Thorough scan with quality tool will likely pinpoint.

nimski62

Did you have the recall done for engine wiring harness being soaked in coolant? (Only applies to 4.2l model)

Chris Brookes

I have got the exact same problem with mine 2011 3.0tdi and all faults stated low voltage as the cause, have just ordered an alternator as is was only giving out 13v, hopefully this will cure it!

MP4.2+6.0

I would replace battery myself long before alternator in general, but would be looking at measuring block type data for actual alternator output. Amps are what matters, though 13V doesn't sound terribly suspect to me anyway. Have you done battery yet?

Chris Brookes

It has gone to a specialist who have tested the battery and said it is good

Chris Brookes

Just out of interest do you have the details of how to do/how long it takes to replace it as they are trying to say it's a 4 hour job which I think is a long time for the alternator? Thanks

MP4.2+6.0

No I don't have specifics and have not lost one on an Audi in any of last three I owned. But estimate doesn't surprise me, or maybe even sounds low unfortunately. If like the V8's, alternator is water cooled so more complexity to remove and replace. If in same location (lower left as you look at engine under the hood/bonnet), it is also pretty jammed in with the exhaust just above it, a main motor mount just behind it, and the engine torque mount in front of it. Not fun.

Chris Brookes

thank you, yes it is water cooled on it

Chris Brookes

Just to update, I had the alternator replaced and it showed 14.4v with no errors. Next morning I had the errors back, battery tested good but was told that it could still need a battery as it may have messed up the battery energy management! Audi did not have a battery in stock and I found out that non genuine batteries don't have the required BEM code. Anyway I used the car over the weekend as I had no way of getting a battery and it now seems to have sorted itself out, I'm thinking it's readdapted itself after a few starts?