Try disconnecting the 02 sensor at the connection >
Originally Posted by
SnakeyesTx
I had to cave in and drop the exhaust. I borrowed a lift at a friend's shop, swapped the sensor, fired up the car and the check engine light was still on. I hadn't disconnected the battery yet so I figure I'll do it when I get home. Halfway home (about 5 miles into a 10 mile trip) the engine gets up to operating temperature and suddenly the light turns off. I can feel the idle issues disappear at short stops and stop signs, and the acceleration even get better. About a block from my house, I'm sitting at a red light for what seemed like forever, and out of the blue, the motor bucks and the idle bogs down like it used to do, and the check engine light comes back on. It's back to its retarded acceleration too. As I pull into the driveway, the light turned off again and idle went back to nice and smooth, aka normal.
Disconnected the battery for over 2 hours, put it back on, started the car, no light, smooth idle, good drivability again.
First red light I get stuck at for more than 2 minutes, bang.. bog down for a second, idle b/s again, check engine light back on. I pull over and stomp test, and sure enough same 1221 code for o2 sensor. The light came on and off all night at various times after that.
So... wtf? It's only kicking the light on when I have to sit at idle for a while at lights. It eventually goes away after driving a few minutes. Problem is, I have to get the car inspected before the month is out and I can't have that stupid light coming on. Anyone have this issue before?
I replaced the o2 sensor with a Bosch OE replacement (#13108) in case anyone wanted to know what was used.
and taking it for a test drive. I was checking mine out this week and disconnected it. The CEL came on after a few minutes, but the car drove fine, both at idle and during acceleration. I hooked it back up and the light went out after about a 1/2 mile and the performance was the same. Guess I am saying, see if you get the same problem without 02 sensor hooked up. If the problem appears, I am guessing something else is causing the CEL. Check your temp sensors to make sure they are within spec.
Jeff in MN
87 535is 245k Recent top end re-work
88 528e 290k
90 535i 115k
98 740i 115k New Magnaflow Cats, No More Codes