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Discussion Starter #1
In the last month or so, my SES light goes on for about 4-5 days when driving in town. Then it goes off for about a week...and repeats this cycle. Just when I am going to take it in to have it checked out..the light goes off. I dont notice anything wrong. After a trip on the freeway it seems to go off. Also, after I drive it cold for a short distance...then park it for an hour...and turn it on...the engine idle surges...just barely but noticeable...from about 500 to 700 for about 5 seconds. Can someone give me a "heads up" before I take it to the dealer...Is it the MAF? I have 32K miles.
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00 ACS E39 M5
 

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Wake:

I believe, but do not quote me, that if the SES does go on, a code is stored in the OBDC for readout. If it is a warm up problem, i.e. always occurs when cold, park the car overnight at the dealer, if possible, and have them verify the problem.

I know not much help, but....
 

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Three words...Peake Research Tool (www.peakeresearch.com) I have found it to be invaluable!

:cheers:
 

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If your car is under warranty, give the dealer a chance. The codes will be stored. They can retrieve them and they should fix it. Knowing what the codes are yourself, however, does help avoid having smoke blown up your .... tailpipe.
 

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chadds1 said:
this is a silly product!! if you reset the code, and the problem still exists..the fault light will just come back on!!!!
This tool doesn't just reset the fault light... it will also tell you what the fault codes are. It is a very useful tool for the DIY's.
 

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BlueBomber said:
It is a very useful tool for the DIY's.
Totally agree. It will pay for itself after the first diagnosis. For example, I was able to diagnose an intake camshaft position sensor fault on my E46 recently and was able to fix it for less than $100. That job goes for around $300 at the dealer. YMMV.
 

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Discussion Starter #8
I am basically looking for someone that has experience these exact problems...I guess I will have to take it in. I dont have warranty..so I hope it isnt vanos or serious.
 

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Wake Champ said:
I am basically looking for someone that has experience these exact problems...I guess I will have to take it in. I dont have warranty..so I hope it isnt vanos or serious.
The problem with this is that many different faults can cause these same symptoms. This is why a code reader would be quite valuable here. You could see what fault was triggering the SES light, rather than just following along with other's diagnoses. The codes would tell you if you had irregular values from the mafs, cps or o2 sensors etc., At least leading you toward a diagnosis.
Mike
 

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Discussion Starter #11
BGregg,

That is one of the best posts I have seen. Step by step with pics and arrows....anyone can follow that. Thanks. Some say cleaning works, some say it doesnt...How did it work on your car??
 

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Wake Champ,

I was still in the warranty period, so I got a brand new MAFS. But I'm out of the warranty period as of this month on my 2001. So I haven't actually done the MAFS cleaning procedure on my car, but am hanging on to the information to be ready to do it in the future. I agree that it is a great writeup done by louv with the pictures.

The reason your symptoms sounded familiar...I had RPMs bouncing around when the car was cold, loss of power until it was completely warmed up, intermittent SES light, and the car ran fine when it was warm. By contrast, when my exhaust camshaft position sensor went out, the only symptom was the SES light intermittent and a change in the pitch of my exhaust note. I didn't notice anything with the RPMs or with power loss (at least in the initial stages up to the point I got it fixed). Haven't had the O2 sensors go out on me yet, so can't comment on that. I'm pretty sure you're dealing with a sensor issue and not the VANOS or something else.

But to be sure what you're dealing with, you probably need to read some codes from the OBDII. Good luck in the troubleshooting.
 

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I've had an intermitant SES light too but in my case I can't detect any change in power or other engine behavior such as idle speed, sounds, etc. I asked a mechanic friend (tech at Global) about it and he said that sometimes aftermarket software (I'm running dinan) will cause the engine to run at the limit of variables monitored by the computer and that it will periodically trip it. If it's not consistently over the limit, the comp will reset the light. He said if the light goes off in a few days and there is no noticable problems/changes, not to worry about it.

Using the tool to identify the fault code sounds like a good idea.
 

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Discussion Starter #14
I agree. But in the meantime, car problems typically have the same or similar "symptoms" I was just curious if anyone experience the same symptoms my car had. Either way...eventually I will be taking it to the dealer. I'm not going to replace the vanos, or MAFS, or anything else on my own because someone had problems like mine, so chill out...it's just a post
 

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Discussion Starter #15
Well.....I took it to the dealer.. Here is what I found out with my SES light.

1) Cam sensor- needs to be replaced
2) Catalytic converters - both need to be replaced

Luckily...although I am out of warranty..BMW warranty covers the Cats...thank god!..from what I here, they are expensive. Im not sure how warranty covers it, even though I am out...but Im not complaining.

Anyone know...why these went bad at only 32,000 miles...?? Also, should I expect better fuel economy and more power??
 

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there is a separate emissions warranty, i think it varries state by state. It's something like 7/70 or 8/80, so that's probably why they're covering it. As to why they went bad? I have that same question, i got a new (RO said remanufactured) cat on my m5, pass side, about a year and 12k miles ago. I had a recent 'catalyst efficiency' code, but no ses. I brought it to the dealer for a couple other things, and mentioned the code. they say i need a pair of new cats! I was surprised, one side is only a year old, not sure if the other side is original or not. Oh well, warranty is paying, so i'll take a new set of cats.
I didn't notice any difference in performance when they replaced the one last year.
I wonder if they would have checked for codes, and found this if i had not mentioned the fault code? My peak code reader has just paid for itself many times over!
Mike
 

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Discussion Starter #17
Yeah I am just glad they cover it. Vanos problems should be covered too...since it was a problem on the 2000 model. The dealer didnt really give me a good reason as to why it happened, but said it "may" have been causing power losses...as well as the cam sensor. I didnt really notice anything...but I could have been used to it.
 

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I wouldn't turn down the free catalytic converter solution...but I'm a little suspicious based on other posts that the computer codes say exactly what the problem is. For example, when my catalytic converters went out on my 540i it was very dramatic. It sounded like popcorn was popping underneath my car and I had trouble even getting the car to go above 80MPH (it was choked off). I haven't had a cat problem on my M5 yet, but this is what I was expecting it to feel like.

Take a look at the following post (although an old one). I wonder if the MAFS will still be an issue to uncover on a future visit for Wake Champ? Anybody else have a similar experience?

http://www.m5board.com/vbulletin/showthread.php?t=18540
 

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Discussion Starter #19
You are right, I did not have any drastic problems like you did. But.."warranty" pays for it, so why should I care. The dealer where I go is very honest about what needs to be fixed. Maybe I just caught the problem early? I just want to know what caused it...to happen at only 30,000 miles
 
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