EPC light, P0341 & P0302, limping/won't run (1.2 AZQ)

Replace camshaft sensor

  • Yes, replace

    Votes: 0 0.0%
  • No

    Votes: 1 100.0%

  • Total voters
    1

alexh

Active Member
Mar 1, 2017
61
1
Hi.
Whilst driving yesterday the car, a 1.2 12v 3 cylinder mk4, dropped down on power dramatically and limped along for a mile before stopping completely. It would sometimes start and sometimes not thereafter. At first my OBD2 reader reported P0606 ECM fault and P0341 Camshaft sensor signal. I had the car recovered. When the recovery arrived it was no longer reporting P0606, and was now reporting P0341 and P0302 (misfire on 2). Unburnt fuel in exhaust was easily smelt.

The coil pack on 2 was replaced by me last year with an off-brand part last year. I've also replaced the other two with bosch and VAG marked coil packs respectively.

When I got home I swapped the coil packs and the car started OK but any throttle above ~1000 leads to stalling and p0341 is reported again. I've ordered another bosch coilpack. Now I'm thinking I should first replace the camshaft sensor as that's the main fault and be prepared to change the coil pack.

It's cheaper for me to replace it rather than buy kit to test it or pay someone else to do that I think, and not too hard to do I believe.

What is the OEM manufacturer for the sensor and part number for it. Should I buy a 'known' brand for this part? Is there anything else I can do to confirm it's a bad sensor rather than another fault for example can I bypass or simulate the camshaft sensor? I do understand the purpose of the sensor and the risk that if the timing actually is out the damage ould be catastrophic.
 
Last edited:

alexh

Active Member
Mar 1, 2017
61
1
Also, I noticed the top ecu mount clip has broken and the ecu has been rattling a bit. The connectors seemed a little loose so I re-seated them.

I am wondering if it being loose could be part of the problem. I've ordered a replacement mount.

If I need a new ecu am I right in thinking I will need vag-com or similar to code it to the car? Should I buy a matching ecu, or the latest version. I'm thinking the last letter of the part number/code designates the update.
 

cheshire cat

Full Member
Dec 28, 2002
1,813
1
cheshire
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you need to fix the mount/connections first as the cam sensor fault could be from that--the car should run on default with a duff sensor--a new ecu will need matching and last letter is an update but is usually backwards compatible
 

alexh

Active Member
Mar 1, 2017
61
1
Thanks for the reply. The ecu connections are now snug and I'm picking up a new mount on Saturday. I suppose there could be other faults in the wiring or damage to the ecu itself from being loose.

I think the camshaft sensor is behind the engine under the intake, is that right? Will the car run with the camshaft sensor wiring disconnected from the sensor?
 
Last edited:

alexh

Active Member
Mar 1, 2017
61
1
I replaced the coil pack, checked the cam shaft (CMP) sensor connection (on top of the engine?), and checked the ECU connections again too.

One of these appears to have resolved the problem. I also ran the car with the camshaft sensor disconnected and it gave error p0342, as I think would be expected.

I think I should've proceeded step wise and then I would know which step has fixed the issue. Now due to the uncertainty I'm worried it could reoccur on my fifty mile commute. I think maybe I need to switch back in the old coil pack and see if it causes any issue. I suppose trying to partially unseat the CMP and ECU connections would be of limited value for trouble shooting.
 

alexh

Active Member
Mar 1, 2017
61
1
The answer I think was no, don't replace the sensor. I found washer fluid or coolant in one of the ECU connectors. Once removed all the problems disappeared.

Does anyone need a very lightly used cam shaft sensor?
 

alexh

Active Member
Mar 1, 2017
61
1
Well, I'm confident that I have identified the problem and unfortunately it has reappeared. Again, it's a very small amount around a couple of pins at the bar of the upper smaller connector and drying the connector resolved it. Can't see how the liquid is getting in though. It almost looks like it's coming up from below, or coming out of the ECU. The ECU seems well sealed up

The liquid is slightly greasy feeling, it didn't feel like washer fluid or coolant between my fingers.
 
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alexh

Active Member
Mar 1, 2017
61
1
The liquid turned out to be coolant. The coolant temperature sensor was somehow allowing coolant to get to the dry side along the pins, and this was then being wicked all the way up to the ECU.

A new sensor and o ring seems to have resolved the problem.
 
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