Glow plugs 101 ***Ver. 2.0***

Well, count me in as a believer in heavy duty aluminum foil !!!
I used to get a GP code every other day - from mostly GP #3 - and once in a while GP #4.
Tried De-Oxit, worked for a while but light came back in days.
Tried tightening ends of boots - light came back in days.
Tried cleaning glowplugs and the inside of boots - light came back in days.
Tried contact cleaner - light... you get the idea....
Short of replacing the harness:
Cha$e's aluminum foil mod is working great !!!

I inserted the foil in #3 and have not had a code in almost two weeks.... amazing...
Thanks for the tip Cha$e !

cha$e said:

Well, it's been a week, and the CEL is still off. Looks like the little balls of tinfoil are doing their job!
Also, that's a great idea about just twisting the two wires together so each wire feeds all 4 plugs, thus no difference in resistance. If the tinfoil solution fails, I'll do that.

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I found that you measure a small voltage across the Glow Plug, and call it normal. What I believe you are seeing is a Thermocouple. Aluminum (Block) and steel (Glow Plug).

I am pushing 90K miles, and have just started looking at the Engine. First time the cover has been off.

Aluminum. Very soft, so that it is easy to strip. VW striped out my Oil Plug, but they did put a coil in to fix it.

Aluminum. I had my wheels freeze on the axle when I got the Flat. 2 1/2 hours for AAA to show up. From the same town? Bought a Tourque wrench for this. The wheel should have been greased! Don't talk to me about Air Wrench. Which gets me back to the Glow Plug. The Book calls for a Low Tourque on them of about 132 in/lbs.

This you will want to get correct! A small wrench.

One more thing about Aluminum. It expands with heat. Makes me wonder why they do not allow an engine warmer?

I like the fact that you saw that residual voltage!

Uncle-Dave

Hi Just to let you know that all you guy's info was very helpfull in marking my diagnostic for my CEL Po672, I simply solder from the harness an electrical wire (Ford starter relais wire) and the other end fits perfectly on the glow plug. Thanks again this a great site

Glow Plug Problems? Or is it?

Over the last few months my engine has been lit up. I have taken my 2002 Golf TDi to the VW Dealership and they said that Glow Plug #2 is no good. Or that it could be the wire harness.

I took the car home and changed all 4 glow plugs and I also changed the wire harness. The egnine light still did not turn off. I then followed the directions on this site and tested all the noted posible problems. The relay test seemed flaky so I changed the relay too. All other tested passed with flying colors. However, the check engine light is still lit.

Now, over the last few days I have noticed a few other problems listed below:
- may temperature gauge does not work (or only works at times)
- my radio reception is getting really bad

This leads me to a few questions. Does the error codes need to be reset in order for the check engine light to turn off? Does anyone have any ideas about what might be causing my new problems?

Your time and knowledge is greatly appreciated,

JJR

jjr said:

This leads me to a few questions. Does the error codes need to be reset in order for the check engine light to turn off? Does anyone have any ideas about what might be causing my new problems?

JJR

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yes, you need to reset the code first to see if it pops up again. From what I know, and experience, the CEL will stay in the memory, and will come back on right then, or some random time later if it's still causing a problem.

Glow Plug problem & More

I decided to go big. I am so sick of dealerships at this point I decided to purchase the Innova CAN-OBDII code reader. The device is great. I reset the code and no more problems. Dealership wanted to charge me at least $50. It is already paying for itself. Only downfall is that if I would have bought it earlier I might not have needed to replace the wire harness or the relay.

However, I still have a problem with the temperature gauge and the radio. Any shared knowledge would be greatly appreciated.

If anyone has any questions about the CAN-OBDII code reader I would be happy to share any information about this device.

JJR

Great info on troubleshooting and fixing a p0380 error. For someone who has not yet experimented under a VW hood , this info makes it easy. The defective plug was replaced, and Advance Auto Parts cleared the CEL. I'm good as new again. This thread should be a sticky.

Sheryl

A cheap alternative to a Multimeter

I found using a 12v test light works well to ID the bad glow plug. Attach the light's lead to the positive pole of the battery and then touch each plug. The light should light if it does not it indicates a possible faulty plug.

I dont really have anything useful to contribute to this thread but I would like to mention that I am another satisfied customer. I stumbled across this in order to figure out how to check my glowplugs ( I havent changed them since I bought the car a year and a half ago), and I think it is an excellent resource. Thanks Wingnut and friends!

Steve

Nice work.

I have been going round in circles with my dealer.

Could it be possible to make a chronological list of Glow Plug systems with the Date, Engine type, and Part Numbers, Glow Plugs and Control Relays?

I have had the These Codes and the Engine Coolant given to me.

I have been able to Put the CEL out with help from the Club, and made a 1,700 mile trip with out incident. Days before I made the trip, I went into the Dealer for the 90K Service. The covers were off under the Dash. Told the desk that I know that the Glow Plug circuits are causing the CEL, but I DO NOT WANT ANY GLOW PLUG PROBLEM FIXED. I want to do it my self. ALSO I DO NOT WANT THE BREAKS WORKED ON EITHER AFTER BEING STRANDED FOR 2 1/2 HOURS ROADSIDE WITH THE WIFE. YOU GUYS STRIPPED OUT THE TREADS ON MY OIL PAN.

I could not believe how folks snapped to when I went in for a simple part after the trip.

I have good reason to believe that they just do not Know Diesels.

I believe that the new Ceramic Rapiterm could be a good thing; however no matter how hard I try, I have been unable to get information on them.

Hey, i tried connecting my meter to the glow plugs and im not getting ANY reading for any of the plugs..batter off..battery on..engine on...possitive to plug..negative to ground...what gives? What am i doing wrong?

Charbs

Have you checked resistance of the glow plugs? Mine were 0.4-0.5 ohms for the good ones, and 240 ohms for the bad one. This is on a PD engine.

hmm

well mines not a PD engine..and i did everything that this tread lists and im gettin about .01 ohms on a 200ohm setting for all the plugs..i must be missing something?

Your meter isn't sensitive enough to really read these things - typical reading of good gp is between .5-.8 or there abouts. If you have a lower setting, use it.

my meter goes at low as 20...and i still get no reading at all..does the engine have to be running or the ignition on so its gettin power from the battery or what?

You are checking resistanct - the gp should be disconnected so there should be no difference if the engine is on or whatever. Simple resistance check.

If you are set on the "20 ohm" setting, you should be able to see something as the reading - again about .5-1 ohm, or much more.

?

ya, its so strange, im doing exactly that..but i get nothing..and the meter works fine, we tested it on other sources...could it be possible that my plugs are SO dead, thats why they all read about .01 on 200 ohm setting? My engine wouldnt work if they were that dead would it?
I dont wanna go spend a ****load of money on a set of new plugs if thats not whats wrong..but it seems like it could be the only reason for this SUPER low reading

Did you check it on the 20 ohm setting? Is this a digital meter?

oh ya..tried everything...nothing gives a reading..if its on 200 i get .01...if its on 20 i get .1

Is it a digital meter?

Basically, if they are all reading the same, they are all probably fine. I assume you get 0 if you put the leads together.

Glowplug update and Explanation?

Thanks for that comprehensive explanation. I learned a lot. I'm basically a Newbie and I havejust bought a 2005 VW NB TDI which has a different engine thatn the one in your photos. I am suffering the interminable neverending CHECK LIGHT dilemma and my fried's VAG comes back with a 17056 Code; Cylinder 2 Glow Plug Circuit (Q11): Electrical Fault. I removed the engine cover and all I saw was what looked like a manifold to the right of the engine compartment containing three glowplugs. Now, after reading the article you wrote I would assume them to be the coolant Glow Plugs, but I cleaned the contacts restarted the engine, did the VAG to clear the codes and had a non-light for about a minute before the whole car seemed to reset and the CHECK LIGHT came back on. So if I'm to find the #2 Glow Plug, where might that be? I could just take the engine apart until I see it, but I figured it might be smarter to just be the unknowing person I am and ask for directions. Also, any other tips for dimming that light would be greatly appreciated. Thanks.

lugh

glow plug mystery

rdkern....
Yes, its a digital meter, and the meter is working perfectly fine, we tested it on multiple sources..can someone re-explain the EXACT steps i should take BEFORE testing the actual glow plug...i must be missing something..either that or my glow plugs are practically dead

The gps generally go by reading infinity - not .1 (or whatever). If they are all reading the same, then they are probably fine.

To test them, you remove the harness, put one lead on the tip where the harness was just connected, and one on a good grounding point. Do not even have the key in the car - nothing needs to be turned on.

Are you getting a gp code? I'm not sure what you are trying to do.

ya

ya...im am gettin a glow plug code..so im just tryin to find out if its actually one of my glow plugs...the 4th one specifally..thats what vag says

Lugh

Under the hard engine cover is a soft foam piece that goes across the valve cover, across the back, back across the valve cover, and across the engine front with two flap like parts. The engine glow plugs are behind these flap like things. The wiring harness looks like 1/4" dia. black plastic tubing. Hope this helps.

Ben

lugh said:

Thanks for that comprehensive explanation. I learned a lot. I'm basically a Newbie and I havejust bought a 2005 VW NB TDI which has a different engine thatn the one in your photos. I am suffering the interminable neverending CHECK LIGHT dilemma and my fried's VAG comes back with a 17056 Code; Cylinder 2 Glow Plug Circuit (Q11): Electrical Fault. I removed the engine cover and all I saw was what looked like a manifold to the right of the engine compartment containing three glowplugs. Now, after reading the article you wrote I would assume them to be the coolant Glow Plugs, but I cleaned the contacts restarted the engine, did the VAG to clear the codes and had a non-light for about a minute before the whole car seemed to reset and the CHECK LIGHT came back on. So if I'm to find the #2 Glow Plug, where might that be? I could just take the engine apart until I see it, but I figured it might be smarter to just be the unknowing person I am and ask for directions. Also, any other tips for dimming that light would be greatly appreciated. Thanks.

lugh

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I grudgingly took my 00 Golf to the the stealer today for a CEL. They called me a couple hours later and said the coolant temp sensor and the glow plug harness were both bad. I OKed their replacement to a tune of $450 (including a $70 diagnostic fee). I went to pick up the car this afternoon and the CEL was still on. Then they told me that the #4 glowplug was bad, but if I wanted to buy one at the counter ($45), they'd put it in for free. I declined.

Now, I have the coolant temp sensor and the glowplug harness they removed from the car. My question is whether I can test either of them now that they are off the car. I want to know if they were troubleguessing when they replaced these items (specifically the harness) or if they actually believed them to be bad.

The coolant temp sensor is 4 prongs. I was expecting only 2 and figuring it should have continuity if it's good and infinite if it's bad, but I'm not sure what to make of the 4 prongs.

The harness - can I check that for continuity between one of the wires on the end and the sockets? Does each wire going in feed 2 of the glow plugs? I realize this method would not be as telling as a voltage drop with it still being on the car, but at least it's something.

I'm going to call the stealer tomorrow and argue about the diagnostic fee because they obviously didn't do a complete job of diagnosing or even a qualiy check on the work.

Bottom line: I brought it to the stealer because I wanted the CEL off and I was willing to pay for the work that needed to be done. They didn't fulfill their responsibility to diagnose completely and accuately.

What do you think?

vavet5308 said:

What do you think?

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Next time, drive right on past the dealer and go to a local guru who knows more about your car.

MOST dealership just throw parts at a car and hope it will fix the problem. Very few of them bother to trouble shoot these days. Your colant temp sensor is a $5 parts and about 10 min to replace yourself with a quick set of hands. As for the glow plug code, I'm sure your harness was fine. They can build up a thin layer of oxidation that acts as a barrier for the voltage. this barrier makes the ECM think it has a bad glow plug because of the resistance. A quick shot of Deoxit D5 would have cured that. Since the harness was changed and the code was still there, I wonder if they bothered to even clear it after the work was complete? if so, then just a glow plug replacement would have probably been all that was required. And if the code was for thew #4 glow plug, it was probably the #1 glow plug that was actually bad.

I would go back there and ask for your $70 back and take them up on their offer to change the plug for free, they usually charge an hour or so labor for that, even though it takes 10 min. And make sure they replace the right one (#1, not #4) if the code was indeed for the #4.

Good luck & let us know how it turns out.

Just a quick FYI for others that may have the P0380 Glow Plug/Heater CKT malfunction on a 2001 Jetta w/111K. I also had a P0118 Engine Coolant Temp Circuit High Input. Both codes were read for me at AutoZone for free (after a $57 trip to the dealer) by the way so thanks for the tip.

I followed Wingnut's procedure and did not find any issues. The harness, fuses, etc. all looked clean. I didn't know what to do, so I took the car to Autozone and had them clear the codes. I have started the car 6-7 times since and the CEL has not come back again. The guy at the store told me that lightning storms in my area (Tampa Bay FL) sometimes cause the faults. Does anyone know if this is true? All appears to be OK and I appear to have saved the $400 that the dealer quoted to fix the glow plugs....

Probably just a bit of corrosion/oxidation in the harness. By removing & replacing it, you made a better conatct. It may stay off for another week, or another year. To be proactive, you can pull the harness off & spray some DeoxitD5 into each terminal to remove the oxidation & clean the conatcts. This should keep your harness good for another few years.

Confused

To check which glow plug is bad do I first have to disconnect the Coolant temp Sensor?

Sorry for such a stupid question