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DIY - crankshaft sensor replacement - V6 4MOTION

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DIY - crankshaft (engine speed) sensor replacement - VW Golf Mk4 V6 4MOTION (2.8L 24V, BDE)

PS - my car is RHD so passenger side is on the left :)

I won't touch on why you might want to do this, but if you do, hopefully this will provide some guidance :)

There may be better ways of doing it but this worked for me. I may have missed one or two screws to be undone so use common sense.

Don't do this work on the car while it is hot - you will burn yourself, it is very tight.

Estimated time: 1-1.5hrs for stage 1, 5-10mins for stage 2, 2-3hrs for stage 3, 1.5-2hrs for refitting of the front of the car. All depending on equipment/skills.

The procedure detailed below should be undertaken only by those competent to do so and at your own risk, I accept no responsibility if you follow this guide and break something!!!

Parts needed:

  • T25 Torx bit
  • T30 Torx bit
  • Something to use the above bits with (battery-powered drill is my preference for speed/ease of use)
  • Phillips screwdriver
  • 13mm spanner/socket
  • Universal joint (3/8" or 1/2" depending on hex bit size)
  • 5mm hex bit
  • Wobble extension bar(s)
  • Axle stands/ramp etc
  • Torque wrench capable of 10Nm and any adapters required to connect to hex bit
  • Crankshaft sensor, part no: 929VG0320 (around £40 new)

Also suggested:

  • Large/long flathead screwdriver
  • Small flathead screwdriver
  • Short flathead screwdriver
  • Pliers
  • Molegrips
  • Lightweight bricks
  • Torch
  • Lubricating oil
  • Small plastic bag or similar
  • A liberal quantity of expletives
  • Multimeter (for stage 2 only)
  • Hammer

There are two (or three) stages to this procedure - stage 1 (dismantling the front of the car), stage 2 (optional - test the existing crankshaft sensor), stage 3 (replacing the crankshaft sensor) - and of course reassembly.

Stage 2 is probably not worth doing in any case as although the check is specific it isn't sensitive - so normal or abnormal, you'll still need to replace the sensor, but it only takes a minute so I've included it.

Stage 1

This can be done with the car on axle stands, or not. I used stands this time and think I would've struggled with a jack after getting the front off due to the radiator being a loose part at that stage - but you may wish to do step 1 first.

  1. Remove the screws from the plastic wheel arches in front of the front wheels. This is easiest if you turn the wheels one way or the other to give a bit more space. Using axle stands gives more space too.
    2013-09-05%2019.06.44small.jpg
  2. Disconnect the plastic bonnet release latch handle. It's held on by a couple of pins that go through the plastic 'jaws' and though it seems fragile can bend quite far. I normally use a large flathead screwdriver and just pivot them apart; they pop over the pins and off.

    2013-09-05%2019.13.15small.jpg

  3. Pop off the front grille with the VW badge on. No screws to undo here - just ease it off where marked and it should pull up and out.
    2013-09-05%2019.19.54small.jpg
  4. Undo the screws marked in red; loosen/ignore the yellow-green one. You'll need to undo it later but it's holding the front on so best not to take it off yet. Same applies to the other side.
    2013-09-05%2019.13.27small.jpg2013-09-05%2019.13.36small.jpg
  5. Unclip/pull out the lower grills . There's some screws behind them; you can undo them if they're holding on the plastic trim otherwise worry about them later. On the passenger side there's a sensor which needs to be unplugged before the trim comes off.
    2013-09-05%2019.24.44small.jpg2013-09-05%2019.24.49small.jpg
  6. Unscrew the other screws holding the plastic trim on. Pull off the trim from around the fenders and slide the whole plastic trim off the front of the car.
    2013-09-05%2019.21.14small.jpg
  7. Finish unbolting the headlights. Disconnect the harness to the back of the headlights (there's a clip on the underside) and gently slide them out. Disconnect the connection marked in blue also (this leads to the bonnet lock)
    2013-09-05%2019.21.55small.jpg2013-09-05%2019.22.03small.jpg
  8. Unclip the cable to the lock from its securings. This is easily done with a small flatbladed screwdriver. Disconnect the Bowden cable from the lock.
    2013-09-05%2020.11.32small.jpg2013-09-05%2020.11.20small.jpg
  9. Undo the screws/bolts marked in red and remove the bumper (warning: heavy). Undo the screws marked in yellow and remove the odd triangular-shaped object and the lock assembly (put this somewhere fairly clean, e.g. in the plastic trim you've just removed, to avoid clogging the lock with stones/dirt). Roughly where the blue circles are there are some bolts securing the radiator to the front of the car. Remove these and the securing screws from the fourth image but do not yet remove the frame.
    2013-09-05%2019.45.07small.jpg
  10. When you remove the frame, the radiator will be unsupported except by piping/cables and may damage these. I suggest finding some objects to support its weight.
    Cautiously slide the frame out, supporting the weight of the radiator by hand (warning: heavy). Once the frame is clear of the radiator, support its weight e.g. with bricks.
    2013-09-05%2020.26.06small.jpg
  11. Stage 1 complete!

Stage 2

Skip the steps marked with an * if you intend on replacing the sensor anyway.

  1. Locate the connector from the sensor to the ECU and disconnect it. This is at the front of the engine block welded next to the oil dipstick guide
    2013-09-05%2020.37.49small.jpg
  2. *There are three pins at the connector, 1-3. 1 is at the flat edge to the connector, 2 is in the middle and 3 is at the curved edge. To check the function, measure the resistance between the pins. 1-2 and 1-3 should have (approaching) infinite resistance; pins 2-3 should have resistance between 480-1000Ω. Outside this spec the sensor needs replacing. Within the spec the sensor may also need replacing due to change in resistance with increasing temperatures or other reasons.
    2013-09-05%2020.37.14small.jpg
  3. Stage 2 complete!

Stage 3

It may be possible to complete this stage entirely from the top, but I expect it's far easier to have the car on stands so you can use both access points as and when (my preferred option).

  1. Remove the old connector from the metal brace. This may be challenging due to rust and lack of space. My method: long screwdriver and hammer to the metal brace to dislodge some of the rust. Apply lubricant oil to metal brace and work it underneath the plastic connector. Wedge a short screwdriver against the base of the flat edge, adjacent to the metal brace, and use elbow grease and expletives to force the connector off.
    2013-09-07%2012.17.44small.jpg2013-09-07%2012.31.37small.jpg
  2. From either top or bottom (I went from underneath), locate the crankshaft sensor adjacent to the oil cooler. Next to it there will be a 5mm hex bolt securing it in place. You may appreciate the lack of space to manouevre any tools here (my hands aren't large) but I was able to undo it using the following method: 5mm hex bit >> universal joint at nearly 90° >> 150mm wobble extension bar >> breaker bar.
    Keep the hex bolt; you'll need it for the new sensor.
    Sorry for the poor quality photo, I didn't have the clearance to see the screen/focus as well as take the photo..
    2013-09-05%2020.50.05small.jpg
  3. Remove the final securing clip half way between the sensor and the connector. This is almost impossible to undo in situ. After 10-15mins I gave up, grabbed both ends of the cable in one hand and pulled hard and the connector pulled clear of its retaining hole. It's just an ordinary clip like the ones earlier but very difficult to undo as there's barely space for fingers let alone tools/eyes.
    2013-09-07%2012.51.46small.jpg
  4. I don't know how sensitive crankshaft sensors are to muck and grime but I wasn't taking any chances. Put the business end in a bag or wrap it in clingfilm or something so you can get it into position without coating it in grime. I suggest lowering it down from the top and loosely clip the connector onto the metal brace to hold it temporarily.
    2013-09-07%2012.57.11small.jpg
  5. Get the sensor into position as much as possible and then remove the bag e.g. with pliers, taking care to keep the important bit away from grime. Insert it into the hole so the socket for the hex bolt lines up and loosely tighten the bolt.
  6. The hex bolt needs tightening to 10Nm. Tighten it out of spec and it can misread so it's important to get it right. I used a similar setup to loosening the old bolt but found it easier to tighten from the top using a hex bit >> universal joint >> 150mm wobble extension >> 3/4"->1/2" adapter >> 30cm wobble extension >> torque wrench. You'll probably also need a few more choice expletives so keep them handy.
    2013-09-07%2014.02.08small.jpg
  7. Get the new connector onto the metal brace. This is fun. There's a ridge across the brace for added tightness (I presume) which makes it nearly impossible to get on, since there's even less room than there was for getting the old one off. I ended up using more lubrication, which you should probably avoid if possible since it may degrade the plastic. I also had to use molegrips (gripping the front end of the brace and the middle of the back (curved end) of the plastic connector as the top is too bendy).
  8. Clip the cable in where the old one was a PITA to remove, if you like. Also connect the ECU cable to the connector.
  9. Start the engine briefly to make sure everything is working as intended.
  10. Stage 3 complete!

Reassemble the front end in reverse order. Once the frame/radiator/bumper are fully secured, test the bonnet lock. If it fails to lock, loosen the screws holding it in place and adjust its position until you get it to lock.

Good luck, and hope this helps!

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My 2002 BDE 4Mo has a misfire between 5 and 6000rpm at which point the EPC light illuminates both when accelerating hard and revving in neutral. Also when starting it always fires straight away but then the idle immediately drops and picks up again, once or twice this has caused it to cut out but it always starts again.

 

Other than this the car goes very well and has always been reliable since I bought it in July.

 

Yesterday after my local garage diagnosed a 16705 (G28 engine speed sensor) fault code I followed all the steps in Stage 2 above and my crank sensor checks out (819 ohms across terminals 2-3).

 

I'm going to take a look at all the old school things like plugs, fuel filter etc (A car I once owned lost power going uphill and changing the fuel filter cured it, turned out the old one was full of rust because the previous owner used to run around with a fiver's worth of fuel in the tank and the first thing I did was to fill it up which helpfully washed the rust off the tank walls as I drove). Air filter looks fairly clean.

 

Anyone have any other suggestions? Thanks and happy new year to all :) 

 

 

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