5-Series (E12,E28, E34, E39, E60)Chat relating to the BMW 5-Series of all generations. Specific models include: BMW 518, BMW 520, BMW 520i, BMW 530i, BMW 528i, BMW 530i, BMW 518i, BMW 524d, BMW 525i, BMW 525e, BMW 528e, BMW 540i, BMW 535i, BMW 520d, BMW 525td, BMW 525d, BMW 530d, BMW 525i/xi, BMW 530i/xi. (BMW 5-Series Forum)
When you pulled the codes for the O2 sensors what exactly the code reads? let me know. What I am getting at is to pin point if its a control limit on the O2 sensor or it is O2 sensor itself going south!!
I am at work now and you may have something like PRE and /or POST Cat O2 with number. In this case I'll check the connection in the plastic box 1st (unlikely though) the plastic connectors for the the pre ones sit on top of engine under the plastic cover where it say BMW on the engine.
When I get CONTROL LIMIT on a particular sensor you know it is overwhelmed trying so hard to compensate for another problem. i.e too lean vs. too rich type of a deal.
Yes and the effect of unplugging the MAF causes miscalculations with the volumetric efficiency of the engine and the calculations programmed into the ECM. Someone with more expertise may be able to tell us more. but I trust you get the idea that eventually you will cause a MIScalculation and/or error and hence a check engine light fault pointing at your MAF.
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