2005 skoda octavia diesel starting issues

2005 skoda octavia diesel starting issues

Author
Discussion

Adrian E

Original Poster:

3,248 posts

175 months

Wednesday 22nd July 2015
quotequote all
Colleague has an old octavia 1.9 pd diesel - fairly high mileage but gets serviced. Has had issues with it failing to start recently, usually after its been used and then sat for a couple of hours. It seems the glow plug light doesn't cycle on the occasions when it fails to start. Went into a local indy recently who fought 2 faulty glow plugs and replaced those, but the behaviour has continued.

Sounds like a potential wiring or sensor fault but wondered if there was anything obvious to check? I have vcds and have offered to check for any returning codes but wondered if there's anything worth logging or specifically checking to rule out any common issues?

Sorry for slightly rubbish description - thats as much as I could establish!

shtu

3,408 posts

145 months

Thursday 23rd July 2015
quotequote all
Adrian E said:
It seems the glow plug light doesn't cycle on the occasions when it fails to start.
That's the key bit of info. It's the engine power relay that's failing. They get dry joints internally, and go open-circuit depending on temperature.

On Golf Mk4s it was relay 109. It's probably the same on the Skoda as it's the same platform, but check. Dealers used to keep stock of these on the shelf as it's a fairly common fault, and they're not expensive (tenner or so last time I bought one).

Don't bother hooking up VCDS, you won't get a code logged for this. As the engine isn't receiving power, it doesn't think it's cranking, so doesn't think there's a problem.

Adrian E

Original Poster:

3,248 posts

175 months

Thursday 23rd July 2015
quotequote all
Thanks for that - done a bit of reading and it sounds like it's a different number on the Mk2 Octavia, but for less than £20 it's worth a try smile

R32

383 posts

251 months

Tuesday 28th July 2015
quotequote all
I've just had a similar thing on a mk2 2.0tdi and it turned out to be the ECU...

Adrian E

Original Poster:

3,248 posts

175 months

Wednesday 29th July 2015
quotequote all
R32 said:
I've just had a similar thing on a mk2 2.0tdi and it turned out to be the ECU...
Funny you should say that (well not really, given the cost!) but my colleague wandered over to tell me the car's been back to the garage and they've ruled out the ECU power relay and diagnosed a faulty ECU...

Looking like a £500+ bill to remove/repair/refit. Looked online and that doesn't seem unreasonable if warranted. Used ECUs seem to run to £200 or so and then they're an unknown quantity.

It's got worse since it first went in, so at least it should have made it easier to diagnose!