Intake manifold&cracked backing plate

Mine just turned 98k miles and had the engine replaced @ 85k, independent mechanic who did this work said if the BMW tech who had replaced the engine was paying attention he would have recommended some items be replaced at that time including these gaskets. The only incremental costs would have been cost for parts or less than $100 since the rest of the job was covered by warranty. But, that's a story for another day...live and learn.

Lou

Tom, I had a vacuum leak at the intake manifold backing plate. I thought fixing this would solve the problem but it did not. The only thing it cleared was the Trans program message I was getting. I still have the CEL problem similar to yours.

Jim '94 740i (M60 but but block replaced)

Where was the vacuum leak?

I removed the connectors to the Motronic for an hour and the code disappeared, only to return when I started the car back up to reset the throttle position. I'm beginning to suspect battery voltage, since I do have a rather old battery and I've noticed I get the CEL immediately upon starting if the car has been sitting for several days. On mornings after the car was driven the day before, no CEL.

In my experience, vacuum leaks don't develop suddenly, but only after something has been worked on. I think I'm going to replace the battery and see what happens.

I seem to be having the same problem. CEL comes on when car first warms up for the day. It's like a switch is thrown. The CEL comes on and the car begins to idle poorly. I have fixed on vacuum leak and the Motronic and O2sensors have been swapped out with no improvement. With regards to the thermostat, was the temp guage reading low is in most failedf Tstat cases or did that appear normal? I would appreciate any help. My dealership is stumpped.

Thought it was also the case with my 94 740 but a careful mechanic diagnosed a couple of leaks + a failed thermostat -- car ran too cold .. both caused the Oxy sensors to try to overcompensate, trigger errors. The other symptoms - poor drive-ability, poor gas mileage also resembled O2 problems but when the leaks were fixed and operating temp brought back to normal the codes were cleared and haven't returned. BTW, the thermostat failed in the wierdest way -- the frame actually snapped and the thing locked up in the open position - thus the car always ran cold. I really didn't pay attention because the weather was warm. Mechanic said it wasn't unusual to see them go that way on the V-8's!

What a difference the repairs have made!

Lou

Hi,

I had this code and our local mechanic couldn't figure it out because, O2 sensor was okay, fuel injector was okay and spark plug was okay.
I took it to the BMW dealer and found out the intake manifold gasket leak.
So, make sure to do a thorough check up before you replace perfectly good O2 sensor or fuel systems.
Good luck.

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