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Thread: Oil overfill possible cause of CPS fault code?

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    Oil overfill possible cause of CPS fault code?

    In the last few months I have had my check engine light on much of the time. As this happened so many times on my other BMW, usually with very benign causes, I procrastinated about having the codes read at the dealer. Then, the other day I was doing my first routine check of engine oil since the last dealer oil service (late in March. I've only put about 300 miles on the car since then) and found the oil level to be very high. We were on a long distance trip at the time and I was a bit concerned about going further with an overfill of oil, so I purchased a simple transfer pump and took some oil out of the engine through the dip stick tube. This oil went into an empty oil container so I was able to measure that it took 0.6 litres to bring the oil level back to the full marker on the stick. We then continued our trip.

    Interestingly, the check engine light went out a short time later and stayed off. Of course, I theorized that there was a direct connection between the overfill and the check engine light, since the light first appeared about 50 miles after my oil service. It had gone out and come back once or twice in the intervening time.

    I had the codes read today and they were all about a camshaft position sensor fault (exhaust, bank 1).

    For the life of me, I can't see how a camshaft position sensor fault could be the result of having half a litre too much oil in the engine, so at this point I conclude this is just a remarkable coincidence, but I would like to hear the opinion of those on the board more technically knowledgeable. Can these two things be related?

    I haven't had the sensor swapped out yet and plan to see if any more fault codes occur before doing so. I'm still a bit suspicious that there was a connection.

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    Team Z8 RRZ8's Avatar
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    I guess you are right about the coincidence Harvey... Was the engine light on at the time you read the codes ? Of course usually the MIL burns at the time the oxyges sensor(s) (our cars have 2 'upstream' and 2 'downsteam') start to measure 'bad' values, and/or oxygen sensors deteriorating...
    Interesting of course is if too much oil (my BMW dealer also overfills a little...) gets burnt (?) and thus causing oxygens sensors to measure this...?

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    I could imagine a connection if my Check Engine faults were from oxygen sensors, but since they were not, it is hard to understand any connection. The funny thing is that there were no further fault codes after I reduced the oil level and the Check Engine light has remained out, even though I have put more mileage on the car since reducing the oil level than when the oil level was too high (about 500 km since reducing level, and about 300 km with high level). To confirm any connection one way or the other, I will not change out the camshaft position sensor unless I record another CPS fault. The next few months will tell an interesting story.

    I'm considering getting a code reader.

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    Hmmmm...had my oil changed immediately prior to winter storage. Noticed the engine light within a day of bringing the car out this spring. Took her in a couple weeks ago and was advised that the CAM sensor was the culprit. She's running much, much better now. The dealer did not mention anything about her having too much oil.

    Had my aux fan replaced too. $950 piece of plastic. BMW gave me a bit of a break on price. Kudos to Bill Stuart for his gracious intercession. He is a true gentleman. I am prompted to look at BMW for a daily driver now as well.

    Also, waiting for another key to ship from Germany. Initially I was quoted $625 for a pair of keys. When I confirmed that BMW does not offer a portable key charger, I decided that I would only get one key. Price dropped to just over $200.

    Getting a bit OT. Must say, I knew the car's performance was a bit impaired when the engine light was on. Sure is nice having her humming along as she should be!

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    Team Z8 RRZ8's Avatar
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    Quote Originally Posted by harvey2 View Post
    I could imagine a connection if my Check Engine faults were from oxygen sensors, but since they were not, it is hard to understand any connection. The funny thing is that there were no further fault codes after I reduced the oil level and the Check Engine light has remained out, even though I have put more mileage on the car since reducing the oil level than when the oil level was too high (about 500 km since reducing level, and about 300 km with high level). To confirm any connection one way or the other, I will not change out the camshaft position sensor unless I record another CPS fault. The next few months will tell an interesting story.

    I'm considering getting a code reader.

    Keep us posted....!

    p.s. what type of code reader are you considering ? I have got a ScanTool, but never read any errors....

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    Quote Originally Posted by RRZ8 View Post
    Keep us posted....!

    p.s. what type of code reader are you considering ? I have got a ScanTool, but never read any errors....
    Haven't shopped around lately, but last year when I was considering one due to my 540i showing faults, I looked at the AutoEnginuity product specifically for BMWs. It was a bit pricey then and my wife convinced me to "just take it to the dealer and have them read it". So, no purchase.

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    Quote Originally Posted by jdillane View Post
    Hmmmm...had my oil changed immediately prior to winter storage. Noticed the engine light within a day of bringing the car out this spring. Took her in a couple weeks ago and was advised that the CAM sensor was the culprit. She's running much, much better now. The dealer did not mention anything about her having too much oil.

    ... Must say, I knew the car's performance was a bit impaired when the engine light was on. Sure is nice having her humming along as she should be!

    Nice to hear it is running well. My engine was running absolutely great all the time, giving no indication of degraded performance.

    It puzzles me that a sensor whose design is basically a magnetic proximity detector that senses the gear teeth on a dry sprocket can go bad so easily. I wonder if the CPS fault code is the result of poor quality signals (like low amplitude, noisy etc.) directly related only to the function of the sensor, or could it be the result of the information from the sensor not making sense, like when the camshaft is not actually moving to its correct position when it is supposed to? If the latter was the case, then perhaps there is a stronger connection between other problems (ones that might affect camshaft positioning function) and the CPS fault code.

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    Black/Black Sean's Avatar
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    I am having a very strange problem and I wonder if anyone esle has come across this.

    My "service engine soon" light goes on and off with no apparent fault. The guys at BMW Dubai can't seem to fix it. My car goes in for two days, the light goes off for a day (or less), then it comes back on.

    It has been doing this for 3 months.

    Someone here had suggested that it is the lower quality (regardless of the higher octane) fuel available in the Middle East.

    Any thoughts?

    Cheers

    Sean
    2002 Black/Black

  9. #9
    Administrator thegunguy's Avatar
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    Get a code reader of your own, and pull the codes. The computer has some history. So, even if the light goes out, the code that caused the light is stored in memory.
    thegunguy

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    Black/Black Sean's Avatar
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    Cheers, Any recommendations on which code reader? I am a little limited here in Duabi, so it may have to be from BMW or online

    Sean
    2002 Black/Black

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    Administrator thegunguy's Avatar
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    Any OBDII reader "should" work. I actually use one on the iPhone, called Rev, connected to a OBDII plug via wifi. It works well on the Z8 and the X5.
    thegunguy

  12. #12
    Team Z8 RRZ8's Avatar
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    Sean, if you are looking for an OBD tool, I personally use an OBD ElmScan (Scantool) connected to my laptop, it works well. But what would you do next? It sounds like BMW Dubai is not really capable of diagnosing the problem, let alone solving it....
    Personally I do not think it is the fuel quality. My best guess would be MAF sensors or Vanos sensors.