Fun with camshaft position sensor on V6

richw · 18th July 2023, 18:20

Hi all,

I've had my 2002 V6 since 2019. Late that year, I had an episode where it refused to start for about three days. I replaced the camshaft position sensor with a new one from DMGRS. All good until summer 2022, when it started refusing to start again.

I narrowed this down to if the car had recently been used, and was still warm... all typical symptoms of camshaft sensor failure! Could I really be so unlucky?

When it refuses to start, I remove the engine cover, remove the camshaft position sensor for about 30 seconds, and then re-fit it. Turn the key, and it starts.

On a whim, I tried putting back the old (original) sensor, but that makes the car take longer to start (every time - even when cold) and ultimately, seems to have the same problem with warm starting.

Have I just been really unlucky and somehow munched through two of these sensors? Or could there be some other reason?

Does anyone have a known good sensor for sale?!

rab60bit · 18th July 2023, 20:07

Quote:

Originally Posted by richw

Hi all,

I've had my 2002 V6 since 2019. Late that year, I had an episode where it refused to start for about three days. I replaced the camshaft position sensor with a new one from DMGRS. All good until summer 2022, when it started refusing to start again.

I narrowed this down to if the car had recently been used, and was still warm... all typical symptoms of camshaft sensor failure! Could I really be so unlucky?

When it refuses to start, I remove the engine cover, remove the camshaft position sensor for about 30 seconds, and then re-fit it. Turn the key, and it starts.

On a whim, I tried putting back the old (original) sensor, but that makes the car take longer to start (every time - even when cold) and ultimately, seems to have the same problem with warm starting.

Have I just been really unlucky and somehow munched through two of these sensors? Or could there be some other reason?

Does anyone have a known good sensor for sale?!

I thought to start the car it requires the crank position sensor to function correctly (reference your initial problem). Immediately once started/firing the cam position sensor takes over the spark ignition timing function. Certainly the 'warm engine/sensor' is a malfunction indication of the cam sensor. Perhaps it was actually an iffy crank sensor initially that 'corrected itself' and not the cam sensor at all. Just a possibility...
21/07/23 Well apparently that was a load of rubbish advice. I though to delete but will leave it for posterity.

richw · 19th July 2023, 21:35

Hmm, the number of posts I read about those sensors! And working out which does which, I was pretty convinced that the camshaft one was only needed for starting, and the crankshaft one was more for running. Could be worth a try, though. Annoyingly, that would be even more expense!

I just find it a bit odd that, by the looks of things, I have a 21 year old sensor which is poorly, but also a 3 year old one with similar symptoms!

Yorkshire GOC · 21st July 2023, 15:08

The Cam position sensor on our cars plays no further part once the car has started - that's why a dodgy Cam sensor only causes non starts - as opposed to a dodgy crank sensor which can cause non starts and stalling.

SD1too · 21st July 2023, 18:50

Quote:

Originally Posted by richw

When it refuses to start, I remove the engine cover, remove the camshaft position sensor for about 30 seconds, and then re-fit it. Turn the key, and it starts.

If this is consistently the case I'd be looking at the security of the fixing screw, the cleanliness of the camshaft and sensor surfaces and whether or not the protrusion of the aftermarket sensor is the same as the factory fitted item. Or, if you're also unplugging the electrical connector there may be an intermittent connection there.

Quote:

Originally Posted by richw

On a whim, I tried putting back the old (original) sensor, but that makes the car take longer to start (every time - even when cold) and ultimately, seems to have the same problem with warm starting.

This suggests that it may not be anything to do with the camshaft sensor at all (unless it's the electrical connector as mentioned above). An increase in the time that it takes the engine to fire indicates that some routine service is probably required.

Simon

richw · 21st July 2023, 18:50

Cool. That's what I thought. So my dodgy start is likely to be camshaft sensor. Or... is there anything basically adjacent to that, which would also be affected by me lifting and re-inserting it? (I can't think of anything, so as crazy as it seems, my 'new' sensor only lasted 2-2.5 years, and that's with very light use)

richw · 21st July 2023, 18:58

Quote:

Originally Posted by SD1too

If this is consistently the case I'd be looking at the security of the fixing screw, the cleanliness of the camshaft and sensor surfaces and whether or not the protrusion of the aftermarket sensor is the same as the factory fitted item. Or, if you're also unplugging the electrical connector there may be an intermittent connection there.

The two sensors are very similar, although the original requires a slightly harder shove to get it in. The DMGRS one also needed a 'link lead'. The o-rings are very similar too. I did also try moving/flexing/unplugging/replugging the electrical connections on the sensor, rather than removing the sensor itself... but no good. Only removing and re-inserting the sensor fixes it.

Either sensor usually has a bit of oil on the end when I remove it. Is that normal?

I have been living with it, but each time it happens, I always have this slight panic that it won't actually restart. It also looks bad... a chap with his 20+ year old Rover and the bonnet up!

SD1too · 21st July 2023, 19:00

Quote:

Originally Posted by richw

So my dodgy start is likely to be camshaft sensor.

"Dodgy" is not really the right word Rich, this sensor either works or it doesn't (I speak from painful experience

). When it fails, the engine spins on the starter motor but there is no firing of any of the six cylinders.

Quote:

Originally Posted by richw

... so as crazy as it seems, my 'new' sensor only lasted 2-2.5 years, and that's with very light use)

That can only be down to a poor quality component.

Simon

SD1too · 21st July 2023, 19:05

Quote:

Originally Posted by richw

The DMGRS one also needed a 'link lead'.

That's ok, all the replacements need a link lead now.

When mine failed last year I bought a genuine MGR sensor and link lead. I've had no further trouble with rapid starts every time. It's a balancing act deciding whether or not to buy aftermarket or genuine. With a critical sensor like this, I tend to sway towards genuine.

Simon

richw · 22nd July 2023, 11:57

When I say 'dodgy start', I mean that it will often fail to start (in exactly the way you described - spins on starter, no firing) if the car has recently been used. If I start the car for the first time in a day, then it's peachy.

You've got me wondering now about genuine vs aftermarket. I can't remember what I bought from DMGRS. Looks like a genuine one is now £25
https://www.dmgrs.co.uk/products/rov...0807b848&_ss=r
(but £52.50 with link lead)

Ah yes... that rings a bell, I think mine was a shade under £50 with the link lead (in 2019). As I've go my 20 year old one in the car now, I can check the DMGRS one... yes, it came in an MG-Rover branded bag with their part numbers. Looks exactly the same as the genuine one on the DMGRS site.

I'm slightly reluctant to buy another, but I suppose I don't need the link lead, this time. Hmm!

18th July 2023, 18:20	#1
richw Avid contributor Rover 75 Saloon Join Date: Sep 2017 Location: Stockton-on-Tees Posts: 243 Thanks: 6 Thanked 64 Times in 49 Posts	Fun with camshaft position sensor on V6 Hi all, I've had my 2002 V6 since 2019. Late that year, I had an episode where it refused to start for about three days. I replaced the camshaft position sensor with a new one from DMGRS. All good until summer 2022, when it started refusing to start again. I narrowed this down to if the car had recently been used, and was still warm... all typical symptoms of camshaft sensor failure! Could I really be so unlucky? When it refuses to start, I remove the engine cover, remove the camshaft position sensor for about 30 seconds, and then re-fit it. Turn the key, and it starts. On a whim, I tried putting back the old (original) sensor, but that makes the car take longer to start (every time - even when cold) and ultimately, seems to have the same problem with warm starting. Have I just been really unlucky and somehow munched through two of these sensors? Or could there be some other reason? Does anyone have a known good sensor for sale?!

21st July 2023, 15:08	#4
Yorkshire GOC I really should get out more....... Rover 75 connoisseur se v6 auto Join Date: May 2014 Location: Hull Posts: 2,069 Thanks: 1,842 Thanked 623 Times in 469 Posts	The Cam position sensor on our cars plays no further part once the car has started - that's why a dodgy Cam sensor only causes non starts - as opposed to a dodgy crank sensor which can cause non starts and stalling. __________________ She came off the Longbridge Line on 20-05-2003 The Silver Machine was the 13th of 160 Rover 75's to come off the production line that day and is the 100th of 527 Starlight Silver Rover 75 2.5 V6 Connoisseur SE Auto saloons listed in the build records produced world wide.

19th July 2023, 21:35	#3
richw Avid contributor Rover 75 Saloon Join Date: Sep 2017 Location: Stockton-on-Tees Posts: 243 Thanks: 6 Thanked 64 Times in 49 Posts	Hmm, the number of posts I read about those sensors! And working out which does which, I was pretty convinced that the camshaft one was only needed for starting, and the crankshaft one was more for running. Could be worth a try, though. Annoyingly, that would be even more expense! I just find it a bit odd that, by the looks of things, I have a 21 year old sensor which is poorly, but also a 3 year old one with similar symptoms!

21st July 2023, 18:50	#6
richw Avid contributor Rover 75 Saloon Join Date: Sep 2017 Location: Stockton-on-Tees Posts: 243 Thanks: 6 Thanked 64 Times in 49 Posts	Cool. That's what I thought. So my dodgy start is likely to be camshaft sensor. Or... is there anything basically adjacent to that, which would also be affected by me lifting and re-inserting it? (I can't think of anything, so as crazy as it seems, my 'new' sensor only lasted 2-2.5 years, and that's with very light use)

22nd July 2023, 11:57	#10
richw Avid contributor Rover 75 Saloon Join Date: Sep 2017 Location: Stockton-on-Tees Posts: 243 Thanks: 6 Thanked 64 Times in 49 Posts	When I say 'dodgy start', I mean that it will often fail to start (in exactly the way you described - spins on starter, no firing) if the car has recently been used. If I start the car for the first time in a day, then it's peachy. You've got me wondering now about genuine vs aftermarket. I can't remember what I bought from DMGRS. Looks like a genuine one is now £25 https://www.dmgrs.co.uk/products/rov...0807b848&_ss=r (but £52.50 with link lead) Ah yes... that rings a bell, I think mine was a shade under £50 with the link lead (in 2019). As I've go my 20 year old one in the car now, I can check the DMGRS one... yes, it came in an MG-Rover branded bag with their part numbers. Looks exactly the same as the genuine one on the DMGRS site. I'm slightly reluctant to buy another, but I suppose I don't need the link lead, this time. Hmm!