Knowledge base on Peake codes for E39 M5 - Page 63

E39LOLZ · 1st October 2011, 15:49

Yesterday morning got the dreaded AA code which is well known around here. However, I have been having code AE that I have been tracking for a while and I have eliminated fuel/vacuum leaks as I have had a smoke and fuel pressure tests performed. I know that the AE code is caused by my mafs and recently started to get the AF code (bank 2) as well. Could it be that bad mafs can cause the AA code to go off? 118K miles and I suspect original mafs or a 2nd set on the way out.

chowdah · 1st October 2011, 16:00

IMO: unlikely.

Sailor24 · 1st October 2011, 18:15

If your car has gone super rich and your passages are partially blocked but not completely blocked it can trigger the code. That does not mean assume that this has happened. Little story I cleaned my CBU out a couple of weeks ago and never saw the code again. This morning I was about to write about my success and the way I got into one of the passages. Started the car and the light came on AA code, so I assumed I did not really clear out enough. Wrong turns out my air pump has decided to only spin slowly.

Diagnose your AA code like you have no other codes. Next cold start go to the front and make sure the fan is running. ETC.

E39LOLZ · 3rd October 2011, 01:59

During the past two cold starts (yesterday and today), the fan has been running and then turned off after a minute or so. I have checked for any soft codes over the weekend and the AA code hasn't returned. I really don't want to start another discussion about the AA code as it has been beaten to death on this board, however, it seems that everyone jumps the gun that CB is present whenever the AA code comes up. Could a faulty air pump cause the AA code as well?

technician117 · 3rd October 2011, 02:30

It's a pretty simple system. If you can hear the pump running than it's probably fine. As far as I know the system consists of the pump, some basic piping to each head, and then there are poorly designed passages that clog up, as I'm sure you read all about already. There is also the electrical half, but if the pump is running then you can rule that out. The only thing other than CBU is maybe a break in the plastic tube from the pump that runs to the metal tube..

Sailor24 · 5th October 2011, 00:55

All true but the carbon may just be in the tubes or just around the corner in the head. I am, if I get time, going to tell my story. I have got air flowing again to a cordless and a piece of cable. The SAP system really should be fully diagnosed before you chip out the problem.

E39LOLZ · 5th October 2011, 04:58

Well today I took the $196 plunge and got two new OEM mafs with housing. Yes, you read that correctly. One time blowout sale from a vendor from ebay. Once they arrive I will swap them in and they should end my AE, AF codes. AA code has been hiding so far. I have heard that once new mafs are installed its like having a supercharger installed. Every now and then I feel a slight hesitation under WOT and along with my AE and AF codes, mafs are most likely the culprit. Will update if those codes return after new mafs are installed.

Sailor24 · 5th October 2011, 16:51

Are you sure they are OEM MAFs. There are a bunch of guys on Ebay claiming the same but they are Chinese junk or VW mafs. If they are OEM send me a link I will buy them and save till I need them.

technician117 · 5th October 2011, 17:33

Quote:

Originally Posted by Sailor24

Are you sure they are OEM MAFs. There are a bunch of guys on Ebay claiming the same but they are Chinese junk or VW mafs. If they are OEM send me a link I will buy them and save till I need them.

+1

Be careful of MAF's on eBay!

manualshifter · 6th October 2011, 09:59

Quote:

Originally Posted by technician117

+1

Be careful of MAF's on eBay!

Can confirm that!

I bought VW Mafs from UK few months back- car would not idle, black smoked etc even after driving for a day and quite a few start stop cycles. Took them out.