buy used '89 240 with 235.000 miles. check engine light on, runs rich, o2 stuck on .9 volt
pull fuel codes ( no ignition codes 1-1-1) # 312 missing anti-knock sensor signal, #213 throttle switch, #221 fuel system compensating for rich/lean fuel mix, #113 injector fault.
replaced o2 with new bosch , now switches voltage.
replaced knock sensor with used from pick and pull, test/measures .07 volts at pin 28 @ ECU conn.
do I need to try a NEW knock sensor if signal is still missing ??
will double check for more vacuum leaks. I have only driven car a short distance since repairs were made. Car seem to run ok and has lots of power but the dam CEL comes on after 3 miles with the above codes.
I did have to gut the CAT though, as it was starting to break apart inside and I don't believe this has any effect on the o2.(ahead of CAT)
I'm not to concerned with #213 or #113 for now.
any suggestions ?? Thanks
peter

Try unplugging the AMM, then start the car and see if there's an improvement in idling conditions. A bad AMM can cause both the 2-2-1 and 1-1-3 codes.

A bad cat should be replaced, the old one was quite valuable intact for precious metal recovery.

Pull the 25A fise behind the battery for a few minutes, replace, then see if the codes come back.

-Ryan
--

Athens, Ohio
1987 245 DL 314k, Dog-mobile
1990 245 DL 134k M47, E-codes, GT Sway Bars, GT Braces
1991 745 GL 300k, Regina, 23/21mm Turbo Sway Bars

The car idles and runs ok. Original BIG problem was the car dying on the road, no power acting like fuel starved. Then read about a bad knock sensor retarding the ignition all the way as to the cause of this symptom. I then changed the knock sensor with an USED one. The car still runs ok but the knock sensor code keeps coming back. Trying to make the car reliable (by keeping the check engine light off) for a friend to drive. Further testing is required I think. Will be trying a NEW knock sensor tomorrow.
thanks
peter