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Discussion Starter #1
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
 

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a lot of the faults are from the battery going dead. the only one i would be really concerned with is the "AA" secondary air flow too low. search the forum for "cbu secondary air". this is potentially a big issue $$$$.
 

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It looks like this car has the carbon build up problem. I don't believe it will affect performance but the light will stay on. 2 fixes, 1 remove the carbon, very expensive or get the powerchip software which will turn off the check engine light. Search is your friend. Many threads on this topic. G/L.
 

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Discussion Starter #4
Thanks for the replies! After reading about the secondary air issue, if that code comes back, 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...
 

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Kudos for getting the DME dump and PPI. AA = Powerchip. If you're not willing to buy/do that, and if your state's emissions testing is stout, that's a problem. You can't read into the AE until they recur post-fuel fix. Never seen 8C before. The seat codes are self explanatory. Note that while the fuel pump and filter were replaced, the relay and tank sensor codes point to separate (unaddressed?) fuel components. Good luck.
 

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Discussion Starter #7
chowdah: I am willing to do the fix, but not willing to assume the CBU risk for the asking price. I would suck to pay $1000 to overwrite the existing Dinan software though. My county in WA is pretty strict on emissions.

From reading around, it looks like some of the codes are probably from the bad batt and fuel pump. The real acid test will be what codes they read this morning.

If the AA does not return and it's the 174/175 codes causing the SES, is it reasonable to assume that it is not CBU?
The car's a pretty good deal, and I'm prepared to do some fixes, but if the AA code returns, I'll probably only get the car if I get $1000 off to do the Powerchip software.
 

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Discussion Starter #8
Well, the good news is the new codes pulled were ascribed to ongoing preignition (possibly to the high-stage Dinan software, an/or sitting with old gas for several months?)

Codes:
175
000-071
130

Any thoughts?
 

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drive the car and during the road test shut off and restart the engine 3-4 times. if the faults dont come back after that then you should be ok.
 

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Discussion Starter #10 (Edited)
The shop said (and my mechanic agreed) that the codes and SES would probably remain until a few tanks of high-octane gas were run through.

I found out the car had MAFs codes a year or so ago, and they were cleaned, but not replaced. It's looking like this is MAFS, bad O2 or both...
 

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The shop said (and my mechanic agreed) that the codes and SES would probably remain until a few tanks of high-octane gas were run through.

I found out the car had MAFs codes a year or so ago, and they were cleaned, but not replaced. It's looking like this is MAFS, bad O2 or both...
Wait, you're not thinking of buying this based on mechanics say so, right? or are they willing to pay what it takes to fix it if the 'few tanks of high-octane gas' doesn't fix it?

A secondary air flow code WILL NOT clear with fresh gas or O2 sensors or plugs or mafs or techron or....
 

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Discussion Starter #12 (Edited)
The AA fault did not return. The new faults are the fuel trim and O2.

I'm buying based on my own mechanic's knowledge of the vehicle, the PPI, and the price. At the price, I am willing to assume a certain amount of risk. I am assuming that I will need to replace the MAF sensors and at least one O2 sensor at a minimum. Even a PC software CBU fix will not be disastrous.

I'm on the plane about to push back, so wish me luck or at least a good lesson.
 

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The AA fault did not return. The new faults are the fuel trim and O2.

I'm buying based on my own mechanic's knowledge of the vehicle, the PPI, and the price. At the price, I am willing to assume a certain amount of risk. I am assuming that I will need to replace the MAF sensors and at least one O2 sensor at a minimum. Even a PC software CBU fix will not be disastrous.

I'm on the plane about to push back, so wish me luck or at least a good lesson.
Sounds like you are informed then. MAFs and o2s are simply maintenance items, they are really not a purchase factor- IMHO.

These motors are robust and will run fine with a wide range of octane... there is really no sound explanation for gas sitting around for a few months to cause a problem, if the car is optimally maintained.

Good luck...travels and purchase!

A
 

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Discussion Starter #14
Thanks for the well wishes ard Since I know some of the service history, I'm fairly confident the MAFs need replacing.

I'm picking it up in 10. I'll post an update tomorrow.
 

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Those numeric codes you gave won't be discernable to most of us, who know the Peake 2-alphanumberic ones (which to some extent can be cross referenced in your first post). I don't think you can safely assume that an AA will "disappear". Further, the D7 fuel sender one is not something that will fire an SES. You can check its presence via the OBD secret menu, test #2. Last, MAFS rarely explicitly throw a code. It's not totally clear from your postings which errors recur after a clearing them.
 

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Discussion Starter #17
Those numeric codes you gave won't be discernable to most of us, who know the Peake 2-alphanumberic ones (which to some extent can be cross referenced in your first post). I don't think you can safely assume that an AA will "disappear". Further, the D7 fuel sender one is not something that will fire an SES. You can check its presence via the OBD secret menu, test #2. Last, MAFS rarely explicitly throw a code. It's not totally clear from your postings which errors recur after a clearing them.
Only the last 3 codes recurred after the PPI. My mechaninc and the inpecting mech. believed they were consistent with MAFs, O2, or both.

a little offtopic but what is the code when the car has CBU issue?
From what I've read, the AA code is the most common indicator, but it usually manifests as multiple codes. A read through this post will give a lot more info.


I just picked up the car last night. The seller was very honest and represented it well. It runs well, is very tight, and the only issues that I could find were the ones he described and sent me photos of. No surprises is good!

I put 5 gallons of 100 octane in it on top of 1/8 tank of 91, just for fun...

Now for the initial 1200 mile road test! :wroom:
 

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Discussion Starter #18
I'm over halfway home already and so far the only casualty is the center underbelly pan due to bad traffic + unavoidable road debris.

This beast is a great highway cruiser, but It does have a hiccup under load at around 1800RPM. Hopefully it's a result of the MAFs/O2.

Only 450 miles to go!
 

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Discussion Starter #19
Well, I made it home fine last night (1500mi later).

The only casualty was the center and left underbody trays due to road debris+traffic.

Ordered MAFs from Bimmerzone and will report on their effectiveness.
 
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