Wingnut
Top Post Dawg
It seems that a very common DTC is the one for the glow plugs (P0380 or 16764). It is a simple procedure to test & diagnose this code & I hope that this quick tutorial can save some of you from an unecessary visit to your dealer. I appologize in advance for the poor quality of the pictures, but even bad pictures can say a 1000 words!
The tools you will need are as follows:
Digital multimeter ($10-20 from most auto parts stores)
10mm socket to remove engine cover
10mm deep socket if plug replacement is necessary
First step is obviously to remove the engine cover and find the glow plug harness.
Remove the harness by pulling on each plug. It pops off like a spark plug wire. With each plug exposed, you can begin testing each one. Set the dial on the multimeter as low as it will go (most only go down to 200) As you can see with my cheap multimeter, it shows a resistance of .5 ohms just from the plating on the leads.
Find a suitable ground for one lead & place the other lead on the tip of the glow plug. Test each one & record the readings. In my case, I had to subtract .5 from the reading to get the actual value of the plug. 3 of the plugs showed a resistance of .8 ohms and one .7 ohms which is within allowable limits.
If you find that you have one or more plugs with either high resistance, no resistance, or a large variation between the 4 plugs, then you have likely diagnosed the problem and the plugs need to be replaced. If they are all the same or within .1 or .2 ohms, then the plugs are not the problem.
If you find a bad one or two, there is a debate on whether to change just the bad ones or all four. Depending on the mileage on your car, it is acceptable to change just the bad one/s. Make sure you test it to see if the resistance is close to the rest otherwise, you will continue to get the CEL. If you have high mileage, you might as well replace them all as you have gotten use out of them and will probably have to perform this procedure again in the near future.
Replacing the plugs is the same as replacing a spark plug. Just spin it out & replace. Make sure not to cross thread the new plugs though. The torque specs for the plugs is 11 ft/lbs. If you don't have a torque wrench, then just snug them in. The thread is very fine and the aluminum can easily strip. After the plugs are in, reattach the harness (make sure each one snaps into place) and then get the code cleared (it will not clear by itself). You can go to your local Autozone or contact a member in your area with a VAG-COM.
If you tested the plugs and all checked out ok, then your code was likely thrown by a bad harness. Why would a harness cause a code? Check out This thread . The monitoring system is very sensitive to resistance variations and that small amount of corrosion caused enough resistance to illuminate my CEL 4 times, each within a few hundred km's after having it cleared. Since I changed the harness, no CEL for 30,000km now.
Some people have been successful with cleaning the tips of their glow plugs and putting an anti oxidant paste in the harness. However, as you can see from the pics in that thread, the surface that was corroded was inbetween the two pieces and can not be cleaned. You could try this approach and it may work for you. It will save you from having to replace the harness and might last indefinately. Check out this thread for some products to use to clean your harness. At the very least, pick up this product to prevent the harness from going bad to begin with. An ounce of prevention.......you know the rest.
If cleaning the harness didn't work for you and you do decide to replace your harness, here is how I did it:
Tools required:
Wire stripping pliers/crimping tool
Butt connectors
Heat shrink tubing
Heat gun or lighter
I started by cutting the wires on the old harness. Cut as close to the flex guard as possible so you have lots of wire to work with. Then cut off the connectors that come on the new harness.
Wiggle the old harness out and the new harness in. Strip a 1/4" of insulation from the end of each of the four ends & crimp on the butt connectors. Don't forget to put the heat shrink tubing on before you crimp.
Use a heat gun or lighter to shrink the tubing to provide a waterproof seal over the conection.
Snap the harness back onto the plugs and put everything back together. As stated above, get the code cleared and you shouldn't have any more CEL issues related to the glow plug system.
If you do need to replace any glow plugs, they are available at many online places for 1/2-1/3 of the price the dealer charges. I have also seen them on E-bay for very cheap, just do a search for 'tdi glow plug'
Disclaimer: This writeup is for information purposes only and is intended to help anyone who feels comfortable around engines. I cannot guarantee that it will fix ALL occurences of a CEL. I hope it will help most of you and at the very least, save you from an expensive visit to the dealer. Good luck.
The tools you will need are as follows:
Digital multimeter ($10-20 from most auto parts stores)
10mm socket to remove engine cover
10mm deep socket if plug replacement is necessary
First step is obviously to remove the engine cover and find the glow plug harness.
Remove the harness by pulling on each plug. It pops off like a spark plug wire. With each plug exposed, you can begin testing each one. Set the dial on the multimeter as low as it will go (most only go down to 200) As you can see with my cheap multimeter, it shows a resistance of .5 ohms just from the plating on the leads.
Find a suitable ground for one lead & place the other lead on the tip of the glow plug. Test each one & record the readings. In my case, I had to subtract .5 from the reading to get the actual value of the plug. 3 of the plugs showed a resistance of .8 ohms and one .7 ohms which is within allowable limits.
If you find that you have one or more plugs with either high resistance, no resistance, or a large variation between the 4 plugs, then you have likely diagnosed the problem and the plugs need to be replaced. If they are all the same or within .1 or .2 ohms, then the plugs are not the problem.
If you find a bad one or two, there is a debate on whether to change just the bad ones or all four. Depending on the mileage on your car, it is acceptable to change just the bad one/s. Make sure you test it to see if the resistance is close to the rest otherwise, you will continue to get the CEL. If you have high mileage, you might as well replace them all as you have gotten use out of them and will probably have to perform this procedure again in the near future.
Replacing the plugs is the same as replacing a spark plug. Just spin it out & replace. Make sure not to cross thread the new plugs though. The torque specs for the plugs is 11 ft/lbs. If you don't have a torque wrench, then just snug them in. The thread is very fine and the aluminum can easily strip. After the plugs are in, reattach the harness (make sure each one snaps into place) and then get the code cleared (it will not clear by itself). You can go to your local Autozone or contact a member in your area with a VAG-COM.
If you tested the plugs and all checked out ok, then your code was likely thrown by a bad harness. Why would a harness cause a code? Check out This thread . The monitoring system is very sensitive to resistance variations and that small amount of corrosion caused enough resistance to illuminate my CEL 4 times, each within a few hundred km's after having it cleared. Since I changed the harness, no CEL for 30,000km now.
Some people have been successful with cleaning the tips of their glow plugs and putting an anti oxidant paste in the harness. However, as you can see from the pics in that thread, the surface that was corroded was inbetween the two pieces and can not be cleaned. You could try this approach and it may work for you. It will save you from having to replace the harness and might last indefinately. Check out this thread for some products to use to clean your harness. At the very least, pick up this product to prevent the harness from going bad to begin with. An ounce of prevention.......you know the rest.
If cleaning the harness didn't work for you and you do decide to replace your harness, here is how I did it:
Tools required:
Wire stripping pliers/crimping tool
Butt connectors
Heat shrink tubing
Heat gun or lighter
I started by cutting the wires on the old harness. Cut as close to the flex guard as possible so you have lots of wire to work with. Then cut off the connectors that come on the new harness.
Wiggle the old harness out and the new harness in. Strip a 1/4" of insulation from the end of each of the four ends & crimp on the butt connectors. Don't forget to put the heat shrink tubing on before you crimp.
Use a heat gun or lighter to shrink the tubing to provide a waterproof seal over the conection.
Snap the harness back onto the plugs and put everything back together. As stated above, get the code cleared and you shouldn't have any more CEL issues related to the glow plug system.
If you do need to replace any glow plugs, they are available at many online places for 1/2-1/3 of the price the dealer charges. I have also seen them on E-bay for very cheap, just do a search for 'tdi glow plug'
Disclaimer: This writeup is for information purposes only and is intended to help anyone who feels comfortable around engines. I cannot guarantee that it will fix ALL occurences of a CEL. I hope it will help most of you and at the very least, save you from an expensive visit to the dealer. Good luck.
