VW Golf Mk 5 (2004) petrol - Intermittently fails to start

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Fri 27 Jan 2017 20:28
VW Golf Mk 5 (2004) petrol - Intermittently fails to start - speedycar53

Went to start my son's VW Golf Mk 5 (2004) petrol which was working fine earlier. Although the engine cranks readily there is no sign at all of the engine wanting to fire up. I notice that the EPC light is not coming on when the ignition key is in the first position as I think it should. I think the exhaust warning light is also supposed to come on initially but doesn't. I initially though immobiliser but that light comes on briefly and then goes out as it should. It has a new battery with plenty of charge.

This is the second time this has happened - both times the car had been left for the day and failed on returning to it. The first time my son ran the battery completely flat cranking it over and next morning it started fine with a jump start. I did use the spare key so cannot say I have eliminated the immobiliser but the light suggests this is all OK.

Any ideas gratefully received.

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Fri 27 Jan 2017 20:52
VW Golf Mk 5 (2004) petrol - Intermittently fails to start - SLO76
Tried the spare key? Could be the chipped key has failed and the car isn't recognising it.
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Fri 27 Jan 2017 22:06
VW Golf Mk 5 (2004) petrol - Intermittently fails to start - speedycar53
Tried the spare key? Could be the chipped key has failed and the car isn't recognising it.

I will try tomorrow on returning to the vehicle stuck in a car park BUT the immobiliser light indicated all is good with the main key.

Does the immobiliser prevent the other warning lights coming on when they should (key in first position)?

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Fri 27 Jan 2017 22:14
VW Golf Mk 5 (2004) petrol - Intermittently fails to start - SLO76
No idea, every manufacturer does it differently. I've certainly experienced faulty keys on many occasions in the past though none were on VAG products to be fair. Nissan and Renault were very common but do share much in the way of electronics and it's the first thing to test before spending any money tracing a fault.

Edited by SLO76 on 27/01/2017 at 22:15

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Fri 27 Jan 2017 22:34
VW Golf Mk 5 (2004) petrol - Intermittently fails to start - elekie&a/c doctor
Unlikely to be the Key.If it was,then the car would fire up an run for a couple of seconds.More investigation required.There are so many possibilities that would cause a non start. A simple check would be to inspect the engine control fuses in the fuse box,end of the dashboard,driver side.make sure contacts are clean and tight.
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Fri 27 Jan 2017 23:23
VW Golf Mk 5 (2004) petrol - Intermittently fails to start - SLO76
"Unlikely to be the Key.If it was,then the car would fire up an run for a couple of seconds."

Not the case with any I've encountered. If the car doesn't recognise the key it'll simply turn over but not start.
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Fri 27 Jan 2017 23:24
VW Golf Mk 5 (2004) petrol - Intermittently fails to start - speedycar53

I am not sure about being the key either but will try the main and then the spare again to see. Will also follow up your suggestion. Thank you.

Edited by speedycar53 on 27/01/2017 at 23:26

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Fri 27 Jan 2017 23:29
VW Golf Mk 5 (2004) petrol - Intermittently fails to start - SLO76

I am not sure about being the key either but will try the main and then the spare again to see. Will also follow up your suggestion. Thank you.

It's just one possibility and the easiest one to check first. I'm not guaranteeing it will be what's wrong but I've seen people chase faults like this that then turn out to be a faulty key. I certainly hope it's something simple and cheap anyway.
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Fri 27 Jan 2017 23:36
VW Golf Mk 5 (2004) petrol - Intermittently fails to start - speedycar53

Me too! My son wants "cheap".

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Fri 27 Jan 2017 23:33
VW Golf Mk 5 (2004) petrol - Intermittently fails to start - speedycar53

I am not sure about being the key either but will try the main and then the spare again to see. Will also follow up your suggestion. Thank you.

Any thoughts as to why the warning lights don't appear with ignition key in first position?

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Fri 27 Jan 2017 23:40
VW Golf Mk 5 (2004) petrol - Intermittently fails to start - SLO76
"Any thoughts as to why the warning lights don't appear with ignition key in first position?"

Ignition switch could be faulty. Had similar on a Toyota Avensis once, had a local auto spark fit a starter button to bypass it. Required the key in but you had to press a button under the dash. Quite liked the added security it brought and cost me all of £50.

Edited by SLO76 on 27/01/2017 at 23:42

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Sat 28 Jan 2017 13:38
VW Golf Mk 5 (2004) petrol - Intermittently fails to start - speedycar53
Tried the spare key? Could be the chipped key has failed and the car isn't recognising it.

I will try tomorrow on returning to the vehicle stuck in a car park BUT the immobiliser light indicated all is good with the main key.

Does the immobiliser prevent the other warning lights coming on when they should (key in first position)?

OK, so I tried the spare key - no different. Ended up towing the car home.

I heard that sometimes disconnecting the battery for a while can reset the electronics so I tried this and bingo. Wish I'd tried that before towing!!

Since the car has refused to start on two occasions just one week apart, there is clearly something not quite right.

The car is now behaving quite normally again until the next time.

I am now not sure whether to get an auto electrician on the case or a mechanic. I guess someone will need to check the fault codes.

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Sat 28 Jan 2017 13:47
VW Golf Mk 5 (2004) petrol - Intermittently fails to start - SLO76
Doubt it's the ignition switch either by the sounds. Might be ECU related if a reset sorted it so possibly a dodgy earth or corroded connector that's causing an intermittent fault. I'd suggest a good auto electrician rather than Joe Blogs mechanic who'll likely just guess his way though a list of bits to change. I've a good spark near me but no use to you unless you're in sunny Ayrshire too.

Sorry I couldn't help, I'm no auto spark. Hope you get it sorted.
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Sat 28 Jan 2017 15:43
VW Golf Mk 5 (2004) petrol - Intermittently fails to start - John F

If it churns and sparks, it's probably lack of fuel. Could it be the fuel pump on its last legs? The jump start might have produced just enough extra oomph to jerk it or its relay into action while not quite blowing its fuse? Just a thought.....there's a lot of chat about fuel pump probs on golf sites/courses...

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Sat 28 Jan 2017 17:29
VW Golf Mk 5 (2004) petrol - Intermittently fails to start - speedycar53
Doubt it's the ignition switch either by the sounds. Might be ECU related if a reset sorted it so possibly a dodgy earth or corroded connector that's causing an intermittent fault. I'd suggest a good auto electrician rather than Joe Blogs mechanic who'll likely just guess his way though a list of bits to change. I've a good spark near me but no use to you unless you're in sunny Ayrshire too. Sorry I couldn't help, I'm no auto spark. Hope you get it sorted.

Thanks. Yes, you have confirmed the conclusion I was reaching. The first time this problem occurred the battery had been run completely flat by my son cranking the engine endlessly and it sprang to life again fine with jump leads. The flat battery was probably equivalent to me disconnecting it for a while second time around hence resetting the ECU on both occasions.

Odd that the problem on both occasions was after the car had been left in a car park all day. Still I suppose a dodgy connection is more likely to manifest itself in cold and damp conditions with condensation as temperatures fall in the afternoon.

I have checked that all the fuses are properly seated in their sockets just in case that was it but all seemed fine.

Terrified about taking to a dealership because they would just replace everything and charge more than the car is worth. I have identified an auto sparks person locally who gets good recommendations and charges reasonable rates so I will give him a call.

Gone are the days when you could just check for a spark at the plug and fuel in the carburettor! Hmm - showing my age.

Thanks for the advice.

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Sat 28 Jan 2017 17:39
VW Golf Mk 5 (2004) petrol - Intermittently fails to start - elekie&a/c doctor

I would guess this is an Fsi engine.In which case you should hear the in-tank pump prime up when you unlock the car and open the drivers door.Tank sits under the rear seat with the pump inside.You may be able to hear it better with the rear seat cushion lifted.

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