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Steve, BMW Expert
Category: BMW
Satisfied Customers: 23903
Experience:  BMW Expert
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Negative OBD datastream readings for engine oil, coolant

Customer Question

negative OBD datastream readings for engine oil, coolant after radiator and internal cabin ranging from -38C to -39.9C. Also recurring fault code for BSD signal interface.
JA: When was your last oil change?
Customer: 7,000 mi ago
JA: What is the model/year of your BMW?
Customer: 2004 x3 e83
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: Yes, cleaned MAF and checked for vacuum leaks ( also been getting fuel trim mixture fault codes but I think it's related to the BSD fault)
JA: Anything else you think the mechanic should know?
Customer: This seemed to start happening after a radiator hose blew and the engine was covered in coolant - steam coming from engine and it reached the redline on the temp gauge
Submitted: 11 months ago.
Category: BMW
Expert:  Steve replied 11 months ago.
what has been attempted so far with regards ***** ***** BSD error?
Customer: replied 11 months ago.
Nothing really. I also get 2882 and 2883 fault codes at the same time, so I checked for vacuum leaks and cleaned MAF sensor to rule that out.
Customer: replied 11 months ago.
seems like the BSD fault might be causing the fuel mixture faults to show up. While driving after engine is warm, there is a sudden but occasional hesitation that I assume is related to the BSD faults and is causing the fuel mixture faults
Expert:  Steve replied 11 months ago.

what is voltage with the engine running?

Customer: replied 11 months ago.
Expert:  Steve replied 11 months ago.

I will provide an honest answer. I trust this will be appreciated. Please remember that a low rating PUNISHES me for being honest and that I receive nothing for my time until a positive rating is clicked.

Thank you for your attention to the rating requirement.

that is too low, should be 14-14.5

along with the BSD faults, this strongly points to a failing alternator so I would suggest replacing yours
Please let me know if you have further questions. Please do not forget to click a positive rating as this is the only way I receive credit for my answer, thank you. Best wishes with your vehicle.

Customer: replied 11 months ago.
The alternator only has 30,000 miles on it. It is from Autozone though. Are there any connections to check on? At one point when I was graphing the engine oil temp it spiked and then dropped back down.
Customer: replied 11 months ago.
I will check the voltage with an actual meter instead of reading the OBD datastream
Expert:  Steve replied 11 months ago.

I would strongly advise a proper BMW alternator despite the cost. many aftermarket ones a) fail prematurely b) do not properly communicate with the engine computer setting bsd faults. not really any connections to check other than the obvious ones at the alternator. Please not forget to CLICK ON a positive rating. If you wish to follow up at a future date you can do so for no additional charge after leaving a positive rating.

Customer: replied 11 months ago.
It's reading 13.9 V with a meter at idle
Expert:  Steve replied 11 months ago.

I would still replace the alternator as this is the place to start in the presence of bsd faults. Please not forget to CLICK ON a positive rating

Expert:  Steve replied 11 months ago.
if there are no additional questions at present please kindly CLICK ON a positive rating