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VW T5 2.5 2008 - Mysterious glow plug fault - Fixed #

Posted by Tony Lewis on February 21, 2018, 12:55 pm

Year of Manufacture *: 2008
( Optional ) Engine Code or CC: 2500

I have a transporter which keeps throwing a fault for cylinder one glow plug. Cutting a long story short I have discovered when the glow plug is installed, the resistance in the plug rises from around 1 ohm to around 3 ohms hence the fault code appearing. Now, the bit I don't understand! If I slacken the glow plug off by around around half a turn or so the resistance changes to what it should be at around 1 ohm. Obviously I have tried a glow plug.

Re: VW T5 2.5 Mysterious glow plug fault.

Posted by aidan birley <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT2879' width='330' height='300' border=0 style='border:none;'> on February 21, 2018, 8:14 pm, in reply to "VW T5 2.5 Mysterious glow plug fault."
Aidan Birley

Hi
Interesting observation, in view of the vastly differing resistance with temperature on a glow plug i would question if that is the reason the ECU is flagging a fault code.

Have you measured Current & Voltage under load? as i feel those readings may be a better indicator,

Of course readings off the other cylinders would be helpful for comparison.

Aidan

Re: VW T5 2.5 Mysterious glow plug fault.

Posted by Antony Powell <iframe src='https://members4.boardhost.com/ukautotalk/info/user=ukat3923' width='330' height='300' border=0 style='border:none;'> on February 22, 2018, 8:06 am, in reply to "Re: VW T5 2.5 Mysterious glow plug fault."

What make of plug are you fitting, who supplied it ?
only ever had similar issue on cheap crap plugs.....

Link: specialist seized injector and glow plug removal services

Re: VW T5 2.5 Mysterious glow plug fault.

Posted by Steve Harrison <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT1363' width='330' height='300' border=0 style='border:none;'> on February 22, 2018, 10:19 am, in reply to "Re: VW T5 2.5 Mysterious glow plug fault."
Stephen Harrison

I would second Tony's observation. Have seen similar with white box glow plugs.

Steve

Re: VW T5 2.5 Mysterious glow plug fault.

Posted by Tony Lewis on February 22, 2018, 2:59 pm, in reply to "Re: VW T5 2.5 Mysterious glow plug fault."
Edited by board administrator February 22, 2018, 3:01 pm

I haven't measured current & voltage but those resistance values are on cold engine with cold plugs. It's not the easiest thing to get at but I will give it a try.

Re: VW T5 2.5 Mysterious glow plug fault.

Posted by Tony Lewis on February 22, 2018, 3:03 pm, in reply to "Re: VW T5 2.5 Mysterious glow plug fault."
Edited by board administrator April 6, 2018, 1:02 pm

NGK plugs. Have checked with NGK to make 100% sure that they are the correct ones.

Re: VW T5 2.5 Mysterious glow plug fault.

Posted by aidan birley <iframe src='https://members4.boardhost.com/ukautotalk/info/user=UKAT2879' width='330' height='300' border=0 style='border:none;'> on February 23, 2018, 8:19 am, in reply to "Re: VW T5 2.5 Mysterious glow plug fault."
Aidan Birley

Hi

If access to the plug is poor you may be able to measure current & voltage at the control unit.

Current will be the same at any point between controller & plug, same is no of course always true for voltage.

Aidan

Fixed #

Posted by Tony Lewis on April 5, 2018, 3:37 pm, in reply to "Re: VW T5 2.5 Mysterious glow plug fault."
Edited by board administrator April 6, 2018, 1:01 pm

Hi,
I fixed this a while ago but haven't had chance to update. It turned out this had had a previous repair on cylinder one due to impact damage to from a foreign body entering the cylinder. I stripped this down to gain better access and reamed out the glow plug hole and once again fitted a new glow plug and it cured the problem. The only conclusion I can draw from this is that there must have been damage around the glow plug causing it to distort when fully tightened (didn't feel tight going in). Thanks for the advice given.

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