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1991 Bonneville LE intermittent cam sensor code


shilohin
10-03-2005, 05:37 PM
I have a 1991 Bonneville LE and I'm getting an intermittent Service Engine Soon light. Checked the computer and it gives me a Code 41, Cam Sensor. I have installed 3 new cam sensors from 2 different companies and still get the intermittent SES light. I replaced the ECM (computer) but not the calibration chip. Still get the same SES light with Code 41. Have cleared the codes many times, but the same code comes back.

When I start the engine cold, I get no light and the engine runs fine. After a few minutes when the engine ***starts*** to warm up, I get the SES light. Sometimes it'll come on and off a few times. Then when the engine is at normal operating temp, I get a steady SES light.

I pulled some of the parts off of the front of the engine and checked the wires and wire conduit. Have not checked the cam magnet yet with a mirror, but didn't think a MISSING magnet would cause an INTERMITTENT problem like this. The car seems to run fine, lots of power and fine gas mileage. Any ideas? Click and Clack didn't know. Ha ha. It's not funny. Thanks for any help offered.

maxwedge
10-03-2005, 06:09 PM
Look at the magnet, then see what is what, if ok post back. The code would only set in closed loop any way.

richtazz
10-06-2005, 04:27 PM
the magnet may not be missing, but the plastic clip that holds it in may be allowing it to move around just enough to not mesh with the sensor. As the engine warms up, the timing chain can get a little loose, allowing the cam to walk throwing off the alignment of the cam magnet and the sensor in the timing cover. Depending on the mileage, you may be in need of a timing chain and gear replacement.

MagicRat
10-06-2005, 07:42 PM
If you do not fix this, eventually the light will come on when you start it up.

The cam sensor is only required upon initial start up, so the sequential EFI is timed correctly. If it loses the cam sensor signal after that, the EFI still functions correctly, the light just tells you the signal is lost.

Eventually, the car will not get the signal upon initial start up, so the EFI goes into a 'batch fire' mode. Although this mode is just to 'limp home' the car will perform well; power, emissions and economy will still be fine. The idle is a bit rougher, and the light is annoying.

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