Knock sensor
Thread Starter
Burning Brakes
Joined: Mar 2003
Posts: 1,174
Likes: 6
From: NW MN
Knock sensor
On my 93 have have gone through the troubleshooting charts to cure a code 43 (knock sensor ckt fault, open/shorted). The knock sensors meter out fine along with the wiring and connectors, however once the car is warm I get intermittant faults. Manual says that if the sensors meter good and the wiring checks out it is a faulty ECM. Before I invest in a ECM I was wondring if anyone else has had a knock sensor go bad after it got warm and was driven for awhile?
Thanks
Thanks
Team Owner
Joined: Oct 2000
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From: Fort Knox, KY
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No, but have you checked the ESC (Electronic Spark Control) module? It's located on the blower motor housing on the passenger side of the engine with the hood raised.
Race Director
Joined: Jun 2001
Posts: 10,956
Likes: 680
From: Marlboro country MA
I had two instances of code 43 being set on my 92 A4. The first time, the problem was inthe ECM itself. The final proof was when we cut the wires going to the knock sensors and spliced in the correct value resistors going to ground. The check engine light still came on right away. I swapped the ECM and the problem instantly disappeared. Then, about a year later, I got an intermittent code 43 that went away when the engine warmed up. This one was fixed by replacing the knock sensors themselves. YMMV.
Thread Starter
Burning Brakes
Joined: Mar 2003
Posts: 1,174
Likes: 6
From: NW MN
Thanks for the replys guys!
MTVette when your ECM was at fault did the code set all the time or was it intermittant? Mine is intermittant but once it comes on it generally stays on and every once in awhile when driving it will go out for a short while and come back on. Always the same stored code 43.
MTVette when your ECM was at fault did the code set all the time or was it intermittant? Mine is intermittant but once it comes on it generally stays on and every once in awhile when driving it will go out for a short while and come back on. Always the same stored code 43.
Race Director
Joined: Jun 2001
Posts: 10,956
Likes: 680
From: Marlboro country MA
86Pace,
When the ECM was faulted, the code and 'check engine' light were always on. Worse, the car was in 'limp-home' mode, with very little power. Suspecting the ECM, I ordered a rebuilt one, but didn't break the shrink-wrapping until the resistor test. It took less than 10 minutes to swap the ECM, and immediately all was fixed.
However, when the problem was the sensor, engine power was never obviously affected. The light was intermittent, and no change in operation (except the light) was effected by replacing the sensors.
When the ECM was faulted, the code and 'check engine' light were always on. Worse, the car was in 'limp-home' mode, with very little power. Suspecting the ECM, I ordered a rebuilt one, but didn't break the shrink-wrapping until the resistor test. It took less than 10 minutes to swap the ECM, and immediately all was fixed.
However, when the problem was the sensor, engine power was never obviously affected. The light was intermittent, and no change in operation (except the light) was effected by replacing the sensors.
