engine speed sensor replacement
10-17-2006, 08:00 PM
#1
AudiWorld Super User
Thread Starter
engine speed sensor replacement
My car began having problems starting up, the engine would turn over but wouldn't catch. This would usually occur usually after being driven and parked for a short period so it seemed heat related. Battery voltage was fine, the battery tested out ok and the alternator seemed ok as well. The worst it got was once I had to let it sit for 15 minutes to cool before it would start but then it was fine.
A couple weeks after this began I was out for a spirited drive and the car shut itself off while cruising at 45mph in 5th gear. I waited about 30 mins with the hood open (luckily it was a cool night) and it finally restarted. I pulled the codes with VAG-Com and it showed two engine speed sensor related faults, an implausible signal and no signal at all. I don't think it threw any codes prior to the shutoff incident but I am not positive that I had checked for any.
The actual part # for my car is 06A 906 433C. The part is common to pretty much all VWs and Audis so I was able to track one down at a local VW dealership (for ~$100). The part is also available at <a href="http://www.ecstuning.com/stage/edpd/pagebuild_v2.cgi?searchstring=ES%231874&searchqt=b yvehicle&make=Audi&model=TT&submodel=Quattro&engin e=225HP">ECS </a>and <a href="http://www.worldimpex.com/search_by_partno.html?searchmode=partno&partno=06A +906+433C&x=0&y=0">Impex</a>(I don't know what the difference is between the two impex parts, the ECS part appears to be correct). There are two variants for this part, the C suffix and L suffix. The C part is about 2ft long overall, the L part is much much shorter (maybe 6"). This is the C part:
<img src="http://lz7w.com/albums/speedsensor/IMG_0064.jpg">
Double check which part you need as I'm not sure if all TTs use the longer part. If your sensor is on the bell housing and the wiring harness is under the intake manifold (you can look in and see it) then you most likely need the C part. Here's a shot thru the rightmost two runners and you can see the grey plug of the speed sensor. You should also be able to read the part # as it is on the wire near the plug.
<img src="http://lz7w.com/albums/speedsensor/IMG_0065.jpg">
Again, this is for a 2001 225hp coupe and this is basically how we replaced it, there may be (have to be) easier ways to do it.
So the replacement, I won't lie.... this sucks. I often tell people how hard it is to get the oil filter out of this car, the sensor is next to the oil filter. With some patience, and a second pair of hands helps(thanks Brad!), it is doable and it took us about 3hrs from wheels up.
Start by getting the car up in the air and removing the undertray. The oil filter is in the way so it needs to be removed. We had a spare filter and 5qts of oil on hand just in case we needed it but we were able to remove the filter without tipping it and only lost about 1/2qt of oil total (thanks to russ scott for the idea of not draining all the oil). Once the filter is out of the way and you've stopped most of the oil dripping out you should be able to get your hand on the sensor. You can see where it is located in this pic from the Bentley:
<img src="http://lz7w.com/albums/speedsensor/speedsensor_vi.jpg">
That pic is deceiving as the only way to get a picture at that angle is to remove the bumper, radiator and core support.
While the oil is dribbling out you can remove some stuff to get access to the plug. Start by removing the plastic engine covers and the plastic cover in front of the dipstick tube. I think this is two phillips screws but I have the <a href="http://42draftdesigns.com/tt_ech.htm">42 Draft Designs</a> engine cover hardware so mine is different.
<img src="http://lz7w.com/albums/speedsensor/IMG_0056.jpg">
Next remove the two 5mm hex bolts that hold the metal bracket in place. You can see one of them highlighted here on the left, the other is on the right side.
<img src="http://lz7w.com/albums/speedsensor/IMG_0057.jpg">
Once that is free slide it up so the tab clears the dipstick tube in the front and rotate it out of the way. You should be able to do this without removing anything that is attached to it. There is a coolant line on the passenger side that passes near the alternator, make sure it ends up back attached to this bracket and not resting on an alternator pulley (just ask my dealership what happens if you don't).
Here the tab is highlighted in the middle of the pic.
<img src="http://lz7w.com/albums/speedsensor/IMG_0058.jpg">
Now you can get the sensor unplugged and unclipped from the dipstick tube. The connector is in a metal bracket and can be slid up off the bracket to make it easier to disconnect it. Once it's out of the bracket there's a tab that needs to be pulled back towards you and that should release the plug from the wiring harness (I think that's what released it anyway). Here you can see the connector in the metal bracket. This side of the connector goes to the car's wiring harness. The male end of the speed sensor plugs into the other side.
<img src="http://lz7w.com/albums/speedsensor/IMG_0059.jpg">
And here it is lifted out of the bracket and you can see the clip that releases the sensor plug from the harness.
<img src="http://lz7w.com/albums/speedsensor/IMG_0068.jpg">
Once it is disconnected you can free it from the clips that hold it to the dipstick tube. There are two clips, one near the top and another further down. The top one shown in the pic below is pretty easy to get to. The bottom one has the wire looped around it to hold it in place and is a bit more difficult to get to. We used a very long pair of pliers to work it out. Also, when we put the new sensor in we replicated the loop to hold it in place on the clip.
You may want to have a spare dipstick tube on hand when you do this repair. As they get old they get brittle and are prone to breaking. You'd be better off having a spare on hand just in case it breaks rather than having another few days of downtime. They are <a href="http://www.ecstuning.com/stage/edpd/pagebuild_v2.cgi?searchstring=ES%231506&searchqt=b yvehicle&make=Audi&model=TT&submodel=Quattro&engin e=225HP"> available</a> at ECS for about $3... cheap insurance.
<img src="http://lz7w.com/albums/speedsensor/IMG_0061.jpg">
Now that the wire is free and the oil is hopefully mostly done dripping you can remove the sensor. There's no straight shot to the sensor that we found and therefore no pics of the process to remove it. There are a bunch of wire bundles in front of the sensor itself which get in the way of actually getting a tool onto it. We were finally able to release a bunch of plastic wire clips and push the bundles out of the way. It takes time to track them down and release them, this is probably the hardest part. I think there were 3 that we ended up releasing.
As you can see from the pic in the Bentley there is a bolt above the sensor.
<img src="http://lz7w.com/albums/speedsensor/speedsensor_vi.jpg">
This is an interesting critter as it is a 10mm hex bolt with a 5mm allen hole in the center. We used a 10mm socket to get it off. Using a 1/4" drive and therefore thinner socket will make this easier as it is tight in there. Also, there is a metal bracket right in front of the sensor which may need to be bent out of the way. As I was unscrewing the bolt my socket backed into the bracket and temporarily jammed everything in place. Once the bolt is out the sensor should come out pretty easily. Note that this is plugged into the bell housing and you want to avoid getting oil in there or on the new sensor.
Install is basically the same order as above. Connect the plug for the new sensor and get it into the clips on the dipstick tube. Drop the new sensor down the front of the block (we put it inside a rubber glove to keep it from getting real nasty). and route it over to the hole in the bell housing. Slide it in and replace the bolt. Put all the wire bundles back into their clips, and replace the oil filter. Put the metal bracket back into the dipstick tube making sure not to pinch any hoses under the bracket and making sure the coolant hose is reattached on the passenger side of the bracket. Put the covers back in place and check your oil, you'll probably be 1/2 to 1 full quart low. Put it back on the ground and crank it up checking for leaks and that everything is back where it should be.
This was done a couple weeks ago but I don't think I forgot anything too important. Please reply here with any tips or tricks you find while replacing yours.
A couple weeks after this began I was out for a spirited drive and the car shut itself off while cruising at 45mph in 5th gear. I waited about 30 mins with the hood open (luckily it was a cool night) and it finally restarted. I pulled the codes with VAG-Com and it showed two engine speed sensor related faults, an implausible signal and no signal at all. I don't think it threw any codes prior to the shutoff incident but I am not positive that I had checked for any.
The actual part # for my car is 06A 906 433C. The part is common to pretty much all VWs and Audis so I was able to track one down at a local VW dealership (for ~$100). The part is also available at <a href="http://www.ecstuning.com/stage/edpd/pagebuild_v2.cgi?searchstring=ES%231874&searchqt=b yvehicle&make=Audi&model=TT&submodel=Quattro&engin e=225HP">ECS </a>and <a href="http://www.worldimpex.com/search_by_partno.html?searchmode=partno&partno=06A +906+433C&x=0&y=0">Impex</a>(I don't know what the difference is between the two impex parts, the ECS part appears to be correct). There are two variants for this part, the C suffix and L suffix. The C part is about 2ft long overall, the L part is much much shorter (maybe 6"). This is the C part:
<img src="http://lz7w.com/albums/speedsensor/IMG_0064.jpg">
Double check which part you need as I'm not sure if all TTs use the longer part. If your sensor is on the bell housing and the wiring harness is under the intake manifold (you can look in and see it) then you most likely need the C part. Here's a shot thru the rightmost two runners and you can see the grey plug of the speed sensor. You should also be able to read the part # as it is on the wire near the plug.
<img src="http://lz7w.com/albums/speedsensor/IMG_0065.jpg">
Again, this is for a 2001 225hp coupe and this is basically how we replaced it, there may be (have to be) easier ways to do it.
So the replacement, I won't lie.... this sucks. I often tell people how hard it is to get the oil filter out of this car, the sensor is next to the oil filter. With some patience, and a second pair of hands helps(thanks Brad!), it is doable and it took us about 3hrs from wheels up.
Start by getting the car up in the air and removing the undertray. The oil filter is in the way so it needs to be removed. We had a spare filter and 5qts of oil on hand just in case we needed it but we were able to remove the filter without tipping it and only lost about 1/2qt of oil total (thanks to russ scott for the idea of not draining all the oil). Once the filter is out of the way and you've stopped most of the oil dripping out you should be able to get your hand on the sensor. You can see where it is located in this pic from the Bentley:
<img src="http://lz7w.com/albums/speedsensor/speedsensor_vi.jpg">
That pic is deceiving as the only way to get a picture at that angle is to remove the bumper, radiator and core support.
While the oil is dribbling out you can remove some stuff to get access to the plug. Start by removing the plastic engine covers and the plastic cover in front of the dipstick tube. I think this is two phillips screws but I have the <a href="http://42draftdesigns.com/tt_ech.htm">42 Draft Designs</a> engine cover hardware so mine is different.
<img src="http://lz7w.com/albums/speedsensor/IMG_0056.jpg">
Next remove the two 5mm hex bolts that hold the metal bracket in place. You can see one of them highlighted here on the left, the other is on the right side.
<img src="http://lz7w.com/albums/speedsensor/IMG_0057.jpg">
Once that is free slide it up so the tab clears the dipstick tube in the front and rotate it out of the way. You should be able to do this without removing anything that is attached to it. There is a coolant line on the passenger side that passes near the alternator, make sure it ends up back attached to this bracket and not resting on an alternator pulley (just ask my dealership what happens if you don't).
Here the tab is highlighted in the middle of the pic.
<img src="http://lz7w.com/albums/speedsensor/IMG_0058.jpg">
Now you can get the sensor unplugged and unclipped from the dipstick tube. The connector is in a metal bracket and can be slid up off the bracket to make it easier to disconnect it. Once it's out of the bracket there's a tab that needs to be pulled back towards you and that should release the plug from the wiring harness (I think that's what released it anyway). Here you can see the connector in the metal bracket. This side of the connector goes to the car's wiring harness. The male end of the speed sensor plugs into the other side.
<img src="http://lz7w.com/albums/speedsensor/IMG_0059.jpg">
And here it is lifted out of the bracket and you can see the clip that releases the sensor plug from the harness.
<img src="http://lz7w.com/albums/speedsensor/IMG_0068.jpg">
Once it is disconnected you can free it from the clips that hold it to the dipstick tube. There are two clips, one near the top and another further down. The top one shown in the pic below is pretty easy to get to. The bottom one has the wire looped around it to hold it in place and is a bit more difficult to get to. We used a very long pair of pliers to work it out. Also, when we put the new sensor in we replicated the loop to hold it in place on the clip.
You may want to have a spare dipstick tube on hand when you do this repair. As they get old they get brittle and are prone to breaking. You'd be better off having a spare on hand just in case it breaks rather than having another few days of downtime. They are <a href="http://www.ecstuning.com/stage/edpd/pagebuild_v2.cgi?searchstring=ES%231506&searchqt=b yvehicle&make=Audi&model=TT&submodel=Quattro&engin e=225HP"> available</a> at ECS for about $3... cheap insurance.
<img src="http://lz7w.com/albums/speedsensor/IMG_0061.jpg">
Now that the wire is free and the oil is hopefully mostly done dripping you can remove the sensor. There's no straight shot to the sensor that we found and therefore no pics of the process to remove it. There are a bunch of wire bundles in front of the sensor itself which get in the way of actually getting a tool onto it. We were finally able to release a bunch of plastic wire clips and push the bundles out of the way. It takes time to track them down and release them, this is probably the hardest part. I think there were 3 that we ended up releasing.
As you can see from the pic in the Bentley there is a bolt above the sensor.
<img src="http://lz7w.com/albums/speedsensor/speedsensor_vi.jpg">
This is an interesting critter as it is a 10mm hex bolt with a 5mm allen hole in the center. We used a 10mm socket to get it off. Using a 1/4" drive and therefore thinner socket will make this easier as it is tight in there. Also, there is a metal bracket right in front of the sensor which may need to be bent out of the way. As I was unscrewing the bolt my socket backed into the bracket and temporarily jammed everything in place. Once the bolt is out the sensor should come out pretty easily. Note that this is plugged into the bell housing and you want to avoid getting oil in there or on the new sensor.
Install is basically the same order as above. Connect the plug for the new sensor and get it into the clips on the dipstick tube. Drop the new sensor down the front of the block (we put it inside a rubber glove to keep it from getting real nasty). and route it over to the hole in the bell housing. Slide it in and replace the bolt. Put all the wire bundles back into their clips, and replace the oil filter. Put the metal bracket back into the dipstick tube making sure not to pinch any hoses under the bracket and making sure the coolant hose is reattached on the passenger side of the bracket. Put the covers back in place and check your oil, you'll probably be 1/2 to 1 full quart low. Put it back on the ground and crank it up checking for leaks and that everything is back where it should be.
This was done a couple weeks ago but I don't think I forgot anything too important. Please reply here with any tips or tricks you find while replacing yours.
10-18-2006, 05:49 AM
#5
thx for the pic post...i think we will all need to do this at one point in our ownership
at least those with earlier years like ours (2001). i didn't think that you can let the engine cool and restart. i remember some that had to have the car flatbedded to the dealer to get them fixed.
i'm wondering if this part will start to fail after 5 years or just a sporadic failure...maybe do a preventative premature swap?
i'm wondering if this part will start to fail after 5 years or just a sporadic failure...maybe do a preventative premature swap?
10-18-2006, 07:58 AM
#7
AudiWorld Super User
Thread Starter
It seems there are warning signs with it, ie the difficult starts,
so you should be able to change it before it fails completely. I think even LiTTespeed's sensor didn't fail completely right away. It had issues and they tried swapping batteries and I think the time they spent working on it allowed it to cool enough for the part to function again. Of course that did eventually end in a most famous flatbed trip.
I have no doubt mine would have failed completely if I had let it go much longer. My car is usually pretty good about letting me know something is about to break
I have no doubt mine would have failed completely if I had let it go much longer. My car is usually pretty good about letting me know something is about to break
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10-18-2006, 09:51 AM
#9
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[edit] Very good, I'll be doing this over the weekend. Some clarification on the C vs L part
These parts are specific to your VIN. The product split happened on 2001 models. It changed from an L to a C in mid year.
** however, the dealer had the wrong part listed for my car! I'd suggest getting the longer of the two and save the hastle of finding out later.
** however, the dealer had the wrong part listed for my car! I'd suggest getting the longer of the two and save the hastle of finding out later.
10-18-2006, 09:56 AM
#10
AudiWorld Super User
Thread Starter
That's interesting
so if you have a late 2001 or beyond car then my writeup isn't of too much use. The sensor must plug in right next to the sensor itself. The wire just isn't long enough to reach much further than that.