obd error- 17748 - Camshaft Position Sensor (G40) / Engine Speed Sensor (G28): Incor. Correlation

[drohrbach]

Can somone give some advice on what to check next. My W8 has been running a little rough, especially at low RPM's. My engine light came on and I read the code given above. I changed out the camshaft position sensor for the intake on bank 1. This did not resolve the problem. It seems like a timing issue but nothing major has been done to the car. I did change plugs on the car recently but that was it.

[BlueSteW8]

If I'm reading my Bentley correctly G40 on the 4.0L is cam position sensor Bank 2 (driver's side), not Bank1 (passenger side).
G28 is indeed the engine speed sensor (RPMs) but the Bentley code section doesn't list the location of the sensor - it does for the 1.8T and 2.8.
I will look at the detail of the engine later to see where it might be.

Try posting on theW8forum.dk, and see if anyone is familier with it.
I just had my bank 1 adjuster and sensors replaced under warranty (as well as the thermostat), but mine had thrown the P0011 code.
My extended warranty more than paid for itself that day.

[drohrbach]

I double checked my Bently and it does indeed say that for engine code BDP the G40 sensor is on bank 1. On all other engines except for the MP fuel injected motors it appears the G40 sensor is on the bank 2 side.

[BlueSteW8]

I am looking in my Bentley (hard copy) on Y764.
Oddly enough, it shows G40, G62, G300 and G301 as all being "Camshaft position sensor, bank 2".
Since each bank has an intake and exhaust cam position sensor that can't be right.
My guess is G300 & G301 are the Bank 2, and G40, G62 are Bank 1?
The wiring diagram then shows
G40 - Cam shaft position sensor
G163(?) - Cam shaft position sensor 2
G300 - Cam shft position sensor 3
G301 - Cam shaft position sensor 4

[drohrbach]

So with all of this, it appears I changed the correct sensor. Again, this had no positvive effect. Any suggestions on next step?

[BlueSteW8]

Well, the next best guess would be the G28 Engine Speed Sensor - I have no idea exactly where that is, however.
I'll see if they show its location in Bentley.

[germanautoman]

i'm having the same problem on a 06 jetta 2.5 same code 17748 engine is also running rough , and at cruising speed it sound like the lifters are making noise, but once you give it gas or let off gas the noise goes away. I also have a code p0300 random misfire , i have replaced coil packs, spark plugs, and even checked for water in the fuel.

[VWTECHBOB$]

This is an early W8. The vehicle is having cam adjuster issues and just does give you the cam adjuster fault. The software system is to early. Good luck

[alaskadub]

RE the Jetta - My trusted mechanic says that this crap screen that restricts the cam exists in many VW and Audi models. The good news for you is that yours will be easier and less expensive to replace. Let us know if that does the trick.


Modified by alaskadub at 3:09 PM 7-23-2008

[black4motion]

Be sure to call VWOA

[germanautoman]

Quote, originally posted by alaskadub »

RE the Jetta - My trusted mechanic says that this crap screen that restricts the cam exists in many VW and Audi models. The good news for you is that yours will be easier and less expensive to replace. Let us know if that does the trick. Modified by alaskadub at 3:09 PM 7-23-2008

so what do you think that needs to be replaced?

[alaskadub]

talk to your tech. Reference the information on these threads regarding the oil screen that is in front of the cam. See if they think that is a likely problem. If he gives you a blank look call a couple other techs and see if they think it sounds like its the problem.

[flavin42]

Modified by flavin42 at 11:40 AM 7-28-2008

[vr6pilot]

Posting here because I have a nearly identical problem on a 2000 VR6 GTI. i.e. "G40 camshaft position sensor/g28 speed sensor incorrect allocation"

the car runs all day but the start up is not as immediate as would be normally (hot or cold) and at low rpm accelerating, the engine just has a burble to it and a steady vibration you can feel (I do have a poly dogbone mount but it didnt' feel this way 2 weeks ago and I've had the poly mount for 9 months). I can still run the engine up in speed and the vibe seems to diminish above 4000 rpm or so and it is also not present while decelerating off the gas.

I've replace my pre cat 02 sensor (had a code for that, now it's gone) resistance checked all of my 8,000 mile old plug wires, new plugs are in, pulled the cam sensor and checked it for metal fuzz accumulation (only the slightest film of gunk on it) cleaned that and reinstalled it. No change.

I'm going to hunt down the G28 on my car and see what's up with that but I really am curious to hear how this turns out on the OP's car.

cheers

[vr6pilot]

bump for some love.

getting ready to pull the timing cover and check my cams

[germanautoman]

the upper timing chain was the problem, the chain was streched badly and the upper tensioner was at its limit. The intake cam had jumped by two teeth. All the chain guides were like new. The lower chain did not seam to be streched at all but we went ahead and replaced it. I think this might be one of many, this car only had 50k on it.

[vr6pilot]

Mine, too, had jumped a tooth or more on the intake cam and possibly one on the exhaust cam. One of the chain guides was in three pieces.

So now we know. Incorrect correlation between your G28 and G40 means your cam timing is bollocks.

[wizgi]

Thought I would chime in on this post. I have an 05 Jetta 2.5L. I took the car to the dealer who said replacing the timing chain may or may not fix the problem. They suggested I replace the engine. I should note that when I dropped it off at the dealer, the car just ran a little rough at idle. When I picked it up it ran rough consistenly and there was a rattle that wasn't there before, but the engine light was out. I think the 'new' issue may have been caused by them but can't prove it.
I took the car elsewhere. The mechanic broke down the engine and said the timing is fine. He discovered the problem to be the vacuum pump, which seemed to be the source of the rattle as well. When he took out the old pump he found that there was a pin missing from the top. After putting it back together and starting it up, the car runs great but the engine light came back indicating the cam sensor, back to square one. So now the car is slow to accelerate and we are going to replace the sensor with hopes it resolves the problem.

[KingVR]

Quote, originally posted by BlueSteW8 »

Well, the next best guess would be the G28 Engine Speed Sensor - I have no idea exactly where that is, however. I'll see if they show its location in Bentley.

The engine speed sensor on the W8 should be in the transmission bellhousing. It reads the signal from an index wheel mounted on the flex-plate/flywheel. Should be located more on the driver's side I believe.

ON the VR6, it would be mounted on the side of the block (towards the front of the vehicle) near the oil cooler closer to the transmission. The index wheel is within the engine block on the crankshaft.