850 cam pos sensor, should last how long please?

kevn · Post by **kevn** » 21 Mar 2011, 22:33

My 1996 850R has clocked 265,000 kms

(165,000 miles). I have the startup miss/stall issue, seems as though the cam sensor may be faulty. It is a metal Bosch unit so must have been replaced (original Volvo item is housed in black plastic). So, assuming my Bosch unit has been installed for 100,000 km plus, is it likely to need replacing? I have no dash lights on. Thanks folks...

Post by **Ozark Lee** » 22 Mar 2011, 02:57

They really don't have a specific mileage or time to a failure point like many of the other components. I have around 252k miles on the original in the '94, somewhere in the 140k to 150k miles on my son's '96 and and I have around 180k on my '96. They all have the original sensor and there has been no problem. My daughter's S70 has somewhere around 125k miles on the clock and I had to replace the sensor a few months ago due to a stalling problem.

Usually the codes will lead lead you to a failing sensor but not always. The engine has to be running for the ECU to post an error code but the engine will not run without a Cam Position Sensor signal.

...Lee

kevn · Post by **kevn** » 22 Mar 2011, 11:36

Thanks for that... so maybe the cam sensor is not my problem, as the engine does start and drive after a few grinds on the starter. Would it be likely to be an intermittent cam sensor fault or do they just stop working?

Post by **Ozark Lee** » 22 Mar 2011, 13:22

The cam sensor is normally fairly binary in that it either works or it doesn't work but as they age the pulse train can get less defined and/or they can start to have thermal problems. If you suspect a cam position sensor problem but the car still runs make sure the sensor wires are well away from the ignition wires. The plug wires can interfere with the signal from both the cam and crank sensors to a point where the ECU doesn't know how to process them.

...Lee

kevn · Post by **kevn** » 23 Mar 2011, 12:46

Again, thank you

The 'thermal' problem is the issue I think. A gradual failing at operating temps. I have ordered a new sensor from FCPGroton.

bobsnow100 · Post by **bobsnow100** » 23 Mar 2011, 14:14

I just replaced my cam position sensor last month. It was intermittent with stalling. Finally it wouldn't start at all. I did pull codes and I had 2 . One code said cam position sensor intermittently missing. The other said no reading from the cam sensor.
I would try to pull the code and you would still get the one that says it is intermitent if that's the problem.
Your temp sensor will also give you a code fault if that is the problem.

kevn · Post by **kevn** » 29 Mar 2011, 17:54

First, thanks FCP Groton, 7 day service from USA to New Zealand from the time of the email order to my door in NZ.

Upon removing my old sensor, I noticed the male plastic attachment clip that goes to the loom was broken, in fact some bits stayed behind in the female part of the loom clip. Rough start due to old excess fuel on the plugs I suppose but a few revs and a quick road-test, car is all good again

Thanks for all replies.