BMW reduced power mode

Michael Technician New Hampshire Posted   Latest  
2009 BMW 335i xDrive 3.0L (N54B30A) 6-spd (A6HP19Z)

I'm more interested in theory of operation at the moment. I have a BMW that came in with a couple misfire codes, and a severely leaking valve cover gasket

After replacing plugs, and gasket, other codes concerning intake and exhaust cam timing appeared.

My question is, once this car goes into reduced power mode, and then kicks the CEL light on, does it either not see or ignore other codes, or should it continue monitoring all systems and storing codes as it picks them up?

Missing DTC
Gerald Manager
Gerald Default

Yes sometimes they do, but what coded do you have?

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Larry Owner/Technician
Larry Default

In this case I would believe it would be less that the dme stopped recording faults and more that it was no longer attempting to control timing, so there wasnt a fault to record during that period.

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David Technician
David Default

In this case I believe Larry is correct. Bmw limp mode will default to not control timing. I would think though that if there were vanos issues before it would have some historic fault codes stored in the DME.

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Todd Mobile Technician
Todd Default

I am not sure what you are asking but I think that you have got some dirt in the VANOS actuators

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Francisco Owner
Francisco Default

Make sure that the camshaft sensor intake and exhaust connectors are in the correct position and well connected

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Manuel Diagnostician
New Jersey
Manuel Default

I’ve had this car come to me after failed valve cover gasket with crossed cam sendors car would barely start and stay running needed to keep gas pedal down smoke filled shop crazy car! Traced wiring to cam sensors which were placed backwards but I highly doubt this is the ops issue it was running so rough and stalling it was easy to diagnose really

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James Owner/Technician
James Default

Never really thought about it but I would guess once it goes into limp mode most if not all other DME monitors are ignored. Would be easy enough to test just disconnect a sensor not related to the original problem when in limp mode and see if it records the fault.

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Michael Technician
New Hampshire
Michael Resolution

I meant to write down the actual codes for this car, but forgot to. I can say we ran across a bulleting about people not putting in the plastic "cage" assembly inside the oil filter, and having dirty oil damaging the cam actuator solenoids. We removed the filter housing/cover and found there was no center plastic "cage" (I'm not sure what the true terminology is) So we replaced the entire…

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