# Fuel trim check engine



## lenmikelcook (Jan 26, 2008)

I have check engine light that the OBD read as fuel trim bank 1 and bank 2. PO170 and PO173. I have read on what fuel trim is but want to know what is required to fix it.


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## crewdog843 (Mar 15, 2006)

What year e38?

CEL is always emissions related. Can be MAF or cam position sensor. If your car is difficult to start when cold, or dies at a stop light, it is most probably the MAF. If the car runs fine but shows a CEL either intermittently or full on, it could be the cam position sensors.

jake


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## lenmikelcook (Jan 26, 2008)

my car is a 1998. Found how to replace cam position sensors in www.e38.org. Are the MAF's easy to replace also?


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## BMW_tech (Sep 20, 2007)

rich or lean condition? Most likely cause(s),intake leak and faulty AMM.


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## twilkins0306 (Aug 11, 2005)

I had same problem. I changed the front O2 sensors and then the code came up again. then replaced the rear o2 sensors and no problem since. I have e38 1999 with 150K miles


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## Black 840Ci (Feb 8, 2008)

More than likely a intake manifold gasket leak, common to all 4.4 engine with a few miles on them!!!!


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