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Discussion Starter #1
I'm having a recurring Service Engine Soon light and wanted to run the codes past the experts here to see if there's a consensus before I order any parts. I purchased the car back in May with 22K miles and the SES light was on at that time. Before purchase, I had a PPI done and the shop pulled a number of old codes from the DME - most notably the four below:

114 (Hex 72) - Exhaust Camshaft VANOS position control - Cyl #5-8
10 (Hex 0A) - Exhaust Camshaft Position Sensor, Cyl #1-4
15 (Hex 0F) - Crankshaft/Camshaft Position Correlation, Cyl #1-4
185 (Hex B9) - Exhaust Camshaft VANOS position control, Cyl #1-4

The shop cleared all the codes and I drove the car 800+ miles home, fully expecting to see a SES light on the way. But, the light never came back. About a month later, I started the car and immediately felt a rough start. Sure enough, the SES light came back on with the same 4 codes as above. I cleared the codes and drove for another month or so until today, which the SES came back on. Same situation as before (rough start) and codes as above, except this time the 185 code is not present.

I'm thinking I should replace the Exhaust CPS on Bank 1 and probably Bank 2 as well. Crankshaft Position Sensor was replaced in 2003 under warranty (only 11K miles ago). Anything else I should be looking at?

Thanks in advance for any advice you guys have to offer!
 

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Hex 72 is either a solenoid leaking or clogged a bit or one of the MOVs has fallen off or failed on the board. It is not likely the sensor even if the sensor is bad.
The other 3 codes all point to one thing and that is the sensor. Maybe the new sensor was bad? Maybe they installed the intake sensor by mistake. Might be they put the old version in and it failed again. Could also be a bad connector or damaged during the install, many reports of this happening. Possibly there could be another fault in it's wiring, not very common though. Never heard tell of one but someone has to be first.

Frankly the old sensor design is faulty, that is why a new sensor was designed and made. If you want to be sure you could switch the sensor to the other side and see if the code follows. I would just bite the bullet and replace all four and be done with that. Four new ones will likely make sure you never have another problem with them for 10 years.
The boards for the vanos have issues and you will find that the smart thing to do is pull them and do the same maintenance that most others have done. There are tons of posts on this idea and lots of DIYs.
Basically the smart thing for you to do is a vanos refresh and avoid any future problems for years to come.
 

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Discussion Starter #3
Thanks! The only sensor that I know has been replaced is the crankshaft position sensor. To the best of my knowledge, all 4 camshaft sensors are the original from 12/00, so I suspect they are all the older, original design.

A preventive VANOS refresh is next on the to-do list.
 

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Really, 22K on a 2001? Nice.

But also strange because it makes it look like the original CPS's crap out due to simple elapsed time rather than a combination of time, miles, and underhood temps.
 

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Discussion Starter #5
Really, 22K on a 2001? Nice.

But also strange because it makes it look like the original CPS's crap out due to simple elapsed time rather than a combination of time, miles, and underhood temps.
Yes sir! Although it's more like 24K now, but I agree that it seems odd that the CPS need to be replaced with this few miles on the car. That said, the Crankshaft Sensor crapped out at 13K, so that seems even stranger still. Oh well, I knew these sensors were a possible failure item when I bought the car, so I'm not completely taken by surprise. lol

 

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I'm not disputing sailor's recommendation to replace that CPS - it's knackered. But why?

The lesson is don't buy an NOS original-design CPS, I guess.
 

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Discussion Starter #7 (Edited)
Follow Up:

I used INPA to help diagnose this problem - and after monitoring the Exhaust CPS values, it became obvious that I had a completely dead Bank 1 Exhaust CPS:


Honestly, I'm still amazed at how well the car drove with a completely dead CPS. It had some minor driveability issues, but I would have expected much worse. I ordered two OE BMW Exhaust CPS, but decided to just replace Bank 1 (US passenger-side) to see how that affected the symptom first. My "after" video is below.


As you can see, I'm now receiving input from the Bank 1 sensor, although it doesn't match/follow the Bank 2 sensor very closely. I drove the car for about 2 weeks (~350 miles) with no repeat SES lights or codes. Then, I replaced the Bank 2 sensor as a preventive measure. It seems to me as the two sensors are closer than they were before, although there are probably a million reasons why they may or may not match at any given moment, so I don't know how conclusive this really is.


Hopefully these videos will help someone else out in the future. Both of my old sensors were indeed the older style and have both been replaced with the new style CPS. Two months and ~900 miles later and no more VANOS codes and she runs quite well!

Thanks to everyone for the help and the ideas!
 
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