Replacing G28 crank sensor

[937carrera]

My car has been cutting out. The problem seems to be getting worse and happens more frequently when the car is hot.

Initially the rev counter would die, the car cough and then you could continue, but the car seemed to be on a more conservative map. Switching off the ignition gave full power again. In the past few days it has started to need a lot of cranking to restart the car, especially when hot.

I have (nearly) concluded that the crank position sensor / speed sensor / G28 sensor (choose what you want to call it) is failing under thermal load. I have tested between pins 2 and 3 and am not getting any continuity whatsoever, I was expcting 500-1000 ohms. Vagcom has been throwing error code 16706 - Engine Speed Sensor (G28): No Signal, P0322 - 35-10 - - - Intermittent.

I have also tested another G28 sensor on my spare engine and most worryingly that also gives no continuity. I am carring out the correct test aren't I ?

I then bit the bullet and removed the starter to remove the sensor for replacement. Despite using my 4mm allen socket and making sure it was pushed home I have managed to round off the bolt.

Are there any tricks or alternate methods to remove the sensor, or am I faced with an engine out job, followed by drilling out of the bolt and retapping

I assume the Bosch ones from Eurocarparts are fine, ARC engine ?

[alexperkins]

That sensor is an absolute sh*t to change. Done it a few times

Its a magnetic sensor, and will look for pulses against the notch on the flywheel as it rotates. Its not as simple as a continuity test.

Bosch ones should be ok. Personally I have only ever used genuine ones from VW

Given its rounded, short of getting grips on it, I would soak it in releaseing agent, attempt to hammer a 5mm allen key into the socket and hope it grabs, but failing that, its an engine out job.

[937carrera]

Thanks Alex.

I've been thinking about this a little more and i'm going to try using a torx or spline bit to see if that can get some purchase. Either that or I'll try and get a chisel in there and knock it round before I resort to geting the engine out. At least I have an engine out of the car to practice on. If either of those work, then I suppose I might be able to get at the bolt by removing the inlet manifold. I'm making the assumption that the use of a hammer near the sensor will probably destroy its ability to function.

Wish me luck

[937carrera]

Today I was lucky

I used my spare angine as practice and used a chisel (for metal, not wood) to create an line and then hammered the chisel further into the line in an anticlockwise direction. Eventually, and after copious amounts of squirty stuff it moved and I was able to remove the sensor.

It looked like this



With access being more difficult with the engine in the car I decided to remove the inlet manifold to have room to work and repeated the exercise

Here's what the engine looked like from the cam cover level



and a close up of the new sensor in position



It's a shame that the bolt only has a 4mm hex and no depth to it, it's only about 3mm deep, another 3mm would make the job so much easier.

Can you buy the proper new bolts seperately ?

[alexperkins]

That was very lucky indeed!!

VW list it as a seperate part N01470213 (M6x15 Socket Head Hex Bolt), however part 17 on the diagram they use is for multiple impulse senders, so theres a good chance that bolt isnt compatible

[937carrera]

........... and I can now say that the cutting out problem has been solved by the new crank sensor. The VW one originally fitted is Bosch anyway, so OEM replacement from ECP

[maxorkaGTI]

How can i change this sensor?Did i have to remove inlet manifold?Starter?Any other options?

[alexperkins]

Starter has to be removed. Its best accessed from underneath, then youll need a small ratchet with a hex bit on it to undo the bolt (it has a very soft head)

[937carrera]

You've done this more times than me Alex, so you have much more experience of the job.

Although more work is involved in removing the inlet manifold, it might be a better route for those with less experience as it does mean that access to the bolt is much easier, reducing the chance that the allen head gets turned.

More work than simply removing the starter and doing the job from underneath to get the bolt undone, but less overall if the bolt head doesn't round off as a result. you pays your money & you takes your choice

i'm ususally pretty good at removing difficult components and have the right tools, but I had problems with removing both my practice sensor and the real one. The practice sensor was out of the car and still had to be chiselled out so on my personal sample of two i say this can be a b***h of a job