[Evergreen24]

I have an SES light with the following codes:

4C18 message error, terminal 15 0x130, DDE Reciever CAS Transmitter
4121 DDE: DDE Main Relay
4BC2 DDE: Air-Mass Flow Sensor

When I read live data from the MAF I see something in the 250-300 range at idle, which will occasionally spike to 1500+, at which point the IDrive display will say “Engine Malfunction: Reduced Power” until I see the live values normalize, at which point the reduced power message will go away.

This comes and goes with no apparent pattern. Maybe once every 3-5 minutes. The exhaust also smells more like DEF when the values go crazy. Could be in my head, but I’m 99% sure it isn’t.

Anyway, I assume this is just a faulty MAF, which are now only about $38, so I have one on order.

Should I disconnect the faulty one in the meantime, rather than let it bounce back and forth between normal and an error state? I’ll probably have to drive about 200 more miles before the new MAF arrives.

[robnitro]

Disconnected will induce limp mode iirc. Low power almost no boost.

[Evergreen24]

Originally Posted by robnitro

Disconnected will induce limp mode iirc. Low power almost no boost.

Correct. But when the sensor's output goes haywire it puts me in limp mode anyway.

I'm thinking it's maybe not the best thing for it to bounce back and forth between normal operation and limp mode every 5 minutes?

[AlpineX]

Car should run ok in limp with no MAF, taking measurements from intake air temp and manifold pressure.
Advisable to get a bosch or quality equivalent, and reset adaptations.

[Evergreen24]

Originally Posted by AlpineX

Car should run ok in limp with no MAF, taking measurements from intake air temp and manifold pressure.
Advisable to get a bosch or quality equivalent, and reset adaptations.

For anyone also in the market for this part, be advised that Bosch is $186.95, and BMW is $34.41 MSRP.

I'm surprised that it is $160 cheaper to buy a genuine BMW part, but it is.

[Yozh]

It’s been on sale lately. Get one.

[AlpineX]

Originally Posted by Yozh

It’s been on sale lately. Get one.

Thanks for the heads up evergreen. Stopped searching after seeing price at FCP which was lower than posted in this thread.