considering M5 purchase - Help with fault codes?

[thegorilla]

Hi all,
I am considering the purchase of a 2000 E39 M5 with approx 110k on it, but the check engine light has been on and off for a while and was on when the seller took it to an indy shop this afternoon to do a pre-purchase inspection. They read the fault codes and cleared them. Later this evening, the light came on again as the seller went to get gas.

Background: It has Dinan software, exhaust but no CAI. New battery installed a few months ago along with fuel pump and filter (fuel pump failed, and old batt got drained too many times). No codes were read or cleared at that time. The car mostly sat in a garage since then.

I could use some assistance interpreting the codes they pulled. I added the descriptions that I could find from the PEAKE Knowledgebase thread:


He is taking it back in the morning to have them read any codes and check the SES light. Is there anything I should ask them to specifically look for?

Quick responses appreciated, as I have to decide by 11 or noon whether to go down and get it or if this is a deal-breaker.

Thanks in advance!

-orn

[jcdavis]

I am unsure of exactly what is going on with this car, but being an owner of a 2000 M5 I would definately not purchase until these items were fixed. It could be any one problem or an array of problems. It looks like it could be anything from a bad secondary air pump, to knock sensor (low grade fuel maybe), Engine temp cool might be a thermostat, or engine temp sensor. None of these problems are going to be extremely cheap to fix. Also, the problems are obviously still there. The codes were cleared and came back the next day. Not sure if I would put any $$$ on this one just yet.

[NNY528I]

Since when does the CEL come on if the seat heaters dont work right?

Are you sure you are getting the correct information from them. You are most concerned about OBD Emmissions codes which most of these are not.

[thegorilla]

Thanks for all the advice.

The mechanic at the shop said a lot of these could be a result of the previous dead/bad/undersized battery providing too low reference voltages to sensors. My mechanic said that the 174/175 could be due to bad MAFs, and this car did have a MAFs issue a year or so ago, but they weren't replaced.

I will find out this morning which codes came back, or new ones. will post as soon as I know the new fault codes.

As of now, I am thinking that if the only codes that are back are MAFs related, I can negotiate a lower price and replace them. If it's a whole bunch of codes again, I think I will pass on it.

[bmwdave37]

Fuel trim faults are probably maf's, but could be vacuum leaks as well. Either way, lots of money.

Engine temp fault is probably a t-stat, lots of money.

The scariest fault to me is the secondary air fault. Are you aware of the clogged air passage problem? It's a possibility. Lots and lots and lots of money.

[thegorilla]

The seller is willing to work with me if it's just the MAFs, so i'm not too worried about that, but after reading about the secondary air issue, that worries me.

If it's the 174, 175 and AA codes together, from what I've read it could either be MAFs or MAFs and CBU. Probably not worth an expensive learning experience unless ti was heavily discounted.

I'm glad the PC fix exists, but it sucks to pay $1000 to overwrite the existing Dinan software...