CR cam position sensor

[bloc]

2010 Jetta TDI, CJAA, 6speed manual, approx 47k miles

On my way to SLC for a ski trip, I don't bring any tools because this car is so new, I won't have problems, right?

Eventually get a limp mode and flashing glow plug light pulling past Moab. Initially I wig out thinking HPFP (with one of 2micron's kits sitting on the bench at home, haven't been able to install it yet), but VCDS (the one tool I brought) reporting

000833 Cam position sensor (G40)
P0341 -000- implausible signal

and 001601 sensor reference voltage A
P0641 -000- open circuit MIL ON

Copy and clear the code, all is good.

For about 200 miles.
Then it comes back. I cycle the key, car runs fine. For about 30 miles. Now it becomes persistant.. as soon as I clear the code and subsequently pass ~2k RPM, the code comes back. Car also runs rough when it isn't in full-on-limp-mode.

So.. has anyone had any issues with the G40 on a CR engine? I see lots of PD stuff but not much for the CR.

changing it looks like a complete pain in the ass.. requiring removal of the timing belt and accessory bracket/fuel pump. I don't see any obvious signs of chafing or anything.. even getting to the plug to check continuity will be a challenge.. I'm not yet sure, but I think it is buried down under the HP EGR valve.

Not having any tools with me, I may have to bring this to a guru in town.
And I haven't even been on the mountain yet.

The good news is it is drivable for now.. though I wouldn't want to go all the way back to austin with it like this..



Thanks a ton for any help
-Justin

 

[bloc]

Small update... I found where the sensor is and pulled the TB cover to have a look. No obvious damage, nothing stuck to the sensor or the teeth that trigger it from the plate behind the cam pulley. Wiring to the plug under the intake manifold looks fine.

Also the guru that lives in my home town says he hasn't ever seen anything like this on a CR engine.

Gonna go buy a voltmeter, some jewelers screwdrivers, and some dielectric grease. All of which I have multiples of already at home.

Never leave home without tools when you own a VW.

 

[bloc]

I see the forum is just as stumped by this as I am.

Last night I went out to the hotel parking lot and tried to do some detective work. Turns out the multimeter I bought didn't come with a battery so that wasn't going to help.. but I figured I'd see what kind of trouble I can get into. I also wanted to see how difficult it would be to change the sensor, in case that is necessary.

I removed the timing cover again.. and using a small mirror and light, it appears that sensor is not getting changed without removing the timing belt, large roller, and pulling the timing housing rear cover away from the head. Even then, I'm not sure how the cover is held against the head.. it seems the water pump may have to come out to pull it away enough.

So I took apart the harness under the intake manifold to check things out there.. all seemed well. Little bit of dirt in the outer part of the plug, but not past the gasket. Terminals seemed fine, uniform, not burned.. wiring on the engine-harness side seemed good. Literally the only thing causing suspicion is I had my HP EGR eliminated with the CR170 turbo.. so that plug is now hanging on the harness a little. That branch goes up to the control valve on the HPFP and that end seems fine.. but it is pulling that branch down maybe 3/4". Other than that, everything seemed good. Car started fine. I left my diagnostic laptop in the hotel room, so I figured I'd clear the codes in the morning.

That actually makes me think (just now).. a couple of the wire colors going to the cam sensor also go to the HP EGR plug, and I assume they are the sensor reference and ground wires.. could that plug being left open cause problems? There isn't anything shorting terminals.. just.. nothing. maybe some dust?

This morning the car starts up great.. MIL still on. use VCDS to clear codes.. the car is now driving perfectly, as if nothing was ever wrong.

not exactly confidence inspiring.. but it does make me think the sensor is probably ok, but maybe the issue is in the harness somewhere. I'm going to go ahead and buy the tools necessary to remove the ECU and trace the wires.. in case I need to do a roadside repair I'll run a wire direct and make a more formal repair once I get back to austin.

Basically, my bentley manual is at home.. can anyone help me figure out what pins on the ecu end of the harness I should be concerned with? 2010 CJAA CR140, wires on the engine-harness side are (pin 2) purple/green, (pin 3) brown/green, (pin 1) yellow/silver

Many thanks for any help..

 

[CLLARK1]

I noticed how difficult it would be to replace the cam position sensor when studying to service the timing belt on my 2010 JSW.I know on some cars they seem to have a service life of around 100,000 miles,and are routinely changed.I am trying to decide whether or not to change it during timing belt service.I do not see any recommendation of changing the cam position sensor on any of the TDI websites.Any information would be greatly appreciated.

 

[bloc]

I spent a good deal of time reading and talking to people, and even with talking to a couple gurus that do TONS of work on these cars, no one else has heard of this issue on a CR engine.

So, I think you are safe to leave it alone.

That said.. I did end up changing the sensor, and the problem has resurfaced once since then. So it clearly wasn't the sensor itself.

Yes, you'd have 80% of the work done already with a timing belt removal.. but the sensor required removal of the cam pulley hub, outer HPFP pulley and HPFP stretch bolts, and a few other things.

If I knew for sure these sensors were failing on other people's cars, I'd say yes.. but in your case it probably isn't worth the cost or extra work.