Crank and cam position sensors required ASAP.

[Si Blythe]

The electrician has diagnosed a crank and possibly a cam sensor failure. To that end does anyone have them for sale or the part numbers. Many thanks in advance.

Simon

[S2central.net]

I'd be dubious that BOTH failed at the same time... how did the 'electrician' arrive at this conclusion ?

The answer better involve use of an oscilloscope unless he is guessing as there is little or nothing to be learnt from measuring resistance across the sensors.

I have a Camshaft sensor tester you can have for £20 which will show if that is dead or alive.

I have to finish some work on a similar tester for the crank & rpm sensors - trying to make these as cheap as possible for plug and play so that people can quickly and easily diagnose a dead sensor without cost and complexity of oscilloscopes etc

[UrS4boy]

The electrician has diagnosed a crank and possibly a cam sensor failure. To that end does anyone have them for sale or the part numbers. Many thanks in advance. Simon

When codes are pulled on an engine that is NOT running, you ALWAYS get a G28 engine speed sensor failed code. Usually safe to ignore that one. If you are getting a G4 crank position sensor code does NOT mean that you have a failed G4 sensor. As Paul suggests, it is very unlikely. Not impossible but unlikely. The problem is without both the G4 and G40 (cam sensor) signals the ECU will not fire the injectors or the coils = no start. Sometimes a G4 code results from a missing crank position pin on the flywheel. http://forums.quattroworld.com/s4s6/msgs/51259.phtml

Here is some G4 Crank Position Sensor and G28 Engine Speed info:

http://forums.quattroworld.com/s4s6/msgs/20986.phtml

Here is some Cam Sensor info, including a DIY for replacement:

http://forums.quattroworld.com/s4s6/msgs/22580.phtml

[S2central.net]

Surely you get a failed RPM (G28) sensor from vagcom when engine is not running - thats the one I always see.

[UrS4boy]

Surely you get a failed RPM (G28) sensor from vagcom when engine is not running - thats the one I always see.

You are right. Too early in the AM for me.

So the G4 code *could* be real (but I doubt it). I would suspect the pin before the sensor.

I am going to edit my post.

[Rusty]

I got caught out by this the other month felt a right plonker.

It's worth inspecting the wiring and giving the plugs a good wiggle. I had an intermittent fault on mine and it was the plug that sits in the rack behind the engine, on the firewall.

[UrS4boy]

It's worth inspecting the wiring and giving the plugs a good wiggle. I had an intermittent fault on mine and it was the plug that sits in the rack behind the engine, on the firewall.

As shown here (link to more info under photo)

http://forums.quattroworld.com/s4s6/msgs/83633.phtml

[Si Blythe]

Thanks guys, I will look into it at the weekend when I get home. Jonny Bravo is sending some parts just in case so fingers crossed it all goes well.

[orangepeel]

iv had this my problem self even tho my car starts and runs a little lumpy untill its warm checked loom back to ecu its seems ok no breaks in wires i even changed g4 and g28 and it still cums up on fault codes when the cars runing but i havent checked the fly wheel pin as it starts up .can you check it from the littel opening on bell housing let me now how you get on .eney body got eney ideas ? ill keep my eye on this thread

[Si Blythe]

Well changed the crank sensor - still no start, changed the ECU - still no start. I am now thinking cam sensor or ignition modules, the flat ones on the bulkhead as they were the only ones I disturbed. I distinctly remember hearing one of them click loudly! Does anyone have a couple of the ignition modules that I could buy? Happy to collect as I really need to get the car sorted by Sunday as I have a course to attend.

[UrS4boy]

Well changed the crank sensor - still no start, changed the ECU - still no start. I am now thinking cam sensor or ignition modules, the flat ones on the bulkhead as they were the only ones I disturbed. I distinctly remember hearing one of them click loudly! Does anyone have a couple of the ignition modules that I could buy? Happy to collect as I really need to get the car sorted by Sunday as I have a course to attend.

Good luck with Sunday. Did you check that the crank position pin was still on the flywheel? A bad Power Output Stage ignition module would take out 2 or 3 cylinders but the rest would still be there for a very lumpy start. (They are transistorized amplifier/switches so I don't know what you heard go CLICK.)

POS info: http://forums.quattroworld.com/s4s6/msgs/15284.phtml

My money is one the G4 pin:

http://forums.quattroworld.com/s4s6/msgs/51259.phtml

or the cam sensor:
http://forums.quattroworld.com/s4s6/msgs/22580.phtml (includes DIY link)

[Si Blythe]

I must admit I am thinking the flywheel sensor has dropped off. I will take the starter motor out when I get chance to try and see if it is there. It seems long term off the road to me as I think I would rather replace the flywheel than try and weld it in situ so that means gearbox off so I may as well do the cambelt at the same time either way she ain't hittin' the road for a while.
I would like to say thanks to Jonny Bravo, he sent me an ECU and cam sensor so at least I could discount them - top bloke!

[newsh]

Just a thought, check the ground wires where they bolt to the inlet manifold

[Rusty]

Take the plugs out from the rack behind the engine and wiggle them about a bit / use some water dispersing spray. It worked for me

[Si Blythe]

Thanks guys, already done that