Author Topic: AFR Problem at Idle ? (Read 2146 times)

Threehz · « **on:** November 23, 2011, 02:16:35 PM »

Ok so after driving a while when I come to a stop and sit at idle for a while my check engine light lights up. The second I give it any gas it goes away.

Turns out it is code 1222 Lambda Control #1 which means the AFR is too lean or rich for longer then 10 seconds. Not great since the list of possible causes is so long but at least it's a start.

Since it is only coming on when I sit at idle for a while this means that it's only getting too rich/lean during idle.

So what would cause me to be too lean/rich only at idle?

Also the car is showing no symptoms as far I can tell.

91 e30m42 · « **Reply #1 on:** November 23, 2011, 03:04:37 PM »

i would check your oxygen sensor as that what happened to mine it went bad before my engine swap...

bmwconnect · « **Reply #2 on:** November 23, 2011, 03:39:20 PM »

O2 sensors failing will get slow and throw a code - *I would swap this out first* A simple bench test with a propane torch and voltmeter can show you if the sensor is still working correctly and swiftly

If you still have a problem, then I would look at the injectors, fuel pressure , & fuel pump, spark plugs, and finally the exhaust gasket at the headers

good luck sir

DesktopDave · « **Reply #3 on:** November 23, 2011, 04:15:32 PM »

Check the O2 heater relay. I'm thinking that the O2 sensor is cooling off too much & throwing a code.

Could also be the usual stuff...vac leak, low fuel pressure, faulty FPR...