Check engine light

[ppdd]

Greetings,

I have a 2001 740i with ~ 70k miles. It has been a great car since I bought it 4 years ago.

An year ago or so I noticed that my check engine light would turn on when the tank was full, turns off when it reached 3/4 and turns on again when it reaches 1/4. Almost like clock work.

I took it to a good mechanic, he read the code and mentioned something about the air mass indicator. I did some reading about it and could not find any correlation between it and the fact that the check engine light seems synchronized with gas level.

So, any ideas?

Thanks,

[lincolnmaster80]

Mayeb your fuel pump is going south...can't keep a good enough pressure outside of 3/4 and 1/4 full...

What was the diagnostic code? Did the indy happen to give that to you? Were there any other codes pulled?

[muleman]

Could be as simple as a faulty fuel cap, the recirculation system is fairly touchy on the E32 at least. This will trigger the CE light. Have you noticed any other issues? A new fuel cap worked for me when I had similar symptoms. Worth a look.

[deji]

I have a 1997 740IL with 150K miles. My Service Engine Soon light came on. I read the code at my local Autozone store. The codes were P0420, P0133 and P07xx. I replaced my pre-cats O2 sensors, fuel filter and cleaned my throttle body with a throttle body cleaned obtained at Autozone. 50 miles after, the Service Engine Soon light went off.