GM experts or car fans here --- question about cam sensor

oldsmobile
ninety-eight
regency

#1

Thanks for your help! I have a 1988 Olds 98 Regency with 43K miles. The car runs like a top, but the service engine light soon is on. The computer gave me code 41: cam sensor failure. I took the car to my mechanic, who said someone had previously tried to reset the cam (probably because of the service engine soon light) and had jammed the interrupter. He said he would recommend the timing sequence/cycle be replaced since the front of the motor will come off for repairing the cam sensor and interrupter. The price he quoted was very reasonable. What do you think? The car runs great, but I just want to take care of a potential issue. Advice appreciated. Thanks!


#2

How long have you had this car? I’ve worked on these things, and this engine is the 3.8L V6. The 3.0L engine doesn’t use the cam sensor. The cam sensor is simply a sensor that bolts to the front of the timing cover from the outside, and reads what he is referring to the interupter bolted to the timing chain sprocket on the camshaft. It is impossible to tell if the problem is the sensor or the interupter without taking it apart. I don’t understand what a jammed interupter he is referring to, since it is statically attached to the cam sprocket, and doesn’t move, except with the cam sprocket. And it is very rare to have one break off. Usually the sensor goes bad, or a wire breaks. Most of these solutions don’t require the timing cover to come off.


#3

Thanks for the reply. I have had the car for 2 weeks. I bought it with the Service Engine Soon light on. The car ran – and runs – flawlessly. I took it to my mechanic today and just wanted the problem with the light corrected. My mechanic said someone had tried recently? to repair the cam sensor and had used pliers or something to pull it out – and broke part of it. The interrupter was jammed up somehow-- pushed back. He said the front of the engine would need to be opened and that the timing cycle should be replaced while the other repair was being done. This guy has done all my work before and always does an excellent job. I guess I just wanted to know how serious a cam sensor error is. The cost for the work (replace cam sensor, interrupter, and timing cycle, including parts) will be about $500. Thanks for your help


#4

A cam sensor is only about $20 and a breeze to bolt on. That vintage has a history of getting oil soaked and needing replacement. I would have thought you would have had some symptom like a miss or stall or something. A cam sensor is essential.

At any rate I think what he is saying is that the front cover on the engine has to come off to get at the cam interrupter to replace it. If the cover is off, at that point you might as well replace the timing gears and chain at the same time since all the work is already done. I think he means timing chain not cycle.

Your choice but normally the chain and gears would be good for 150,000 or so, so seems a little over-kill but depends on how those gears look when its opened up. I just don’t understand why there isn’t more than a check engine light for the cam sensor.


#5

I’d try replacing the cam sensor and go from there rather than start ripping into the engine. The 3.8 is a near bullet-proof engine and with only 43k miles it should have many years of life left in it.
The cam sensor can be tested with a VOM to weed out any guesswork.