Golf 2.0 FSI engine starting problems

[AdamD]

This morning when I went to start my Golf (2005 2.0 FSI Comfortline auto), I was initially unable to start it. I turned the key to the ACC position, got all the usual dash lights, radio switched on, etc. When I turned the key to the start position, all I got was a single 'click', but nothing more. I switched off the radio (RCD-510) and tried again, and the car started first time, with practically no hesitation, and didn't sound like it was down on voltage (although I don't have a voltmeter to check). The car got a brand-new battery 2 weeks ago (a brand-new Bosch, supplied and installed by Transporter). Ambient this morning was 8 degrees C - so fairly cool.

I was a bit concerned, but I filed it away into the 'things I must get checked soon' list. I drove the car for around 30 minutes, and then left the car parked for about 2 hours. I had switched the radio off before I turned the car off, so it was off when I turned the ignition back on when I got back to the car. I turned the key and got the exact same problem - not once, but perhaps half a dozen times, it refused to turn over at all. After a few attempts I didn't even hear a click anymore. I disabled the interior lights and still no good. Headlights and other ancillaries all worked fine. I thought I was going to have to get the car towed, but tried again 5 minutes later, and it started first time - and as it had in the morning, the starter didn't sound like it was labouring with low voltage, it just started right up with no delay.

I had experienced this type of problem a couple of times a month or two back, but these were both on cold starts after not having driven the car for several days, and I knew the battery was struggling (it was 7 years old and didn't like going a week or so between the car being driven; I had put the issue down to a lack of battery charge and assumed a new battery would fix it). Now that I have a new battery, and given how easily the car does start when it actually does turn over, I'm wondering if I might have a failing starter motor or some other electrical problem.

I scanned the car with VCDS when I got home. The only issues (other than an unrelated NOx sensor code) are these faults in the Central Electrics module, which have been present since I got the car about 9 months ago:

3 Faults Found:

02403 - Terminal 15 for Interior
012 - Electrical Fault in Circuit

00185 - Control Circuit; Relay for Supply Voltage Terminal 15
010 - Open or Short to Plus - Intermittent

02402 - Control Circuit for Terminal 15 for Interior
010 - Open or Short to Plus - Intermittent

Can anyone hazard a guess at what the problem might be? Any idea what "Terminal 15 for Interior" is for, and if the above faults might be related to the starting issue?

Many thanks guys!

(And I've just checked the car now, after it's been sitting for 3 hours in my garage. Car started straight away, three times now, with no issues... Gotta love intermittent faults.)

[Umai Naa!!]

Ignition switch, perhaps? They used to crap out a lot on MK6s, so I presume its the same part.

[AdamD]

Ignition switch, perhaps? They used to crap out a lot on MK6s, so I presume its the same part.

Possible, although I wouldn't expect to hear any click from the starter (or engine bay) if the ignition switch was dying?

[Umai Naa!!]

Also look into Terminal 15 supply relay #433 in the E-box in the engine bay.

Next time the fault occurs, give it a tap and see what happens.

[gandv]

Battery terminals can be a possible factor too, even when they look perfectly clean on the surface. Getting a new battery doesn't necessarily mean the terminal connection is now perfect. Worth a look if you can. If you get stuck - loosening the clamps slightly and rotating them back or forth to freshen up the contact, is well worth trying - just make sure you have a small shifter/spanner(s) that will fit the clamps, in the boot, just in case. (Umai Naa!! suggestions sound good)

[AdamD]

Ignition switch, perhaps? They used to crap out a lot on MK6s, so I presume its the same part.

Also look into Terminal 15 supply relay #433 in the E-box in the engine bay.

Next time the fault occurs, give it a tap and see what happens.

Interesting; a quick google suggests that Terminal 15 is all about ignition power, and the starter is on that circuit:

VWVortex.com - Relay Terminal 15 installed
Question Golf 1.6FSI Terminal 15 Relay
00576 - Terminal 15: Electrical Fault In Circuit - Advice Please - MkV (Mk5) Golf, Golf Plus & Jetta - uk-mkivs

That last link, although referring to different codes (still Terminal 15 related), does suggest the ignition switch may be to blame. I guess it's just one link in the chain though. Maybe the relay itself is the first place to look.

[Umai Naa!!]

Relay is cheap and easy.

Ignition switch is still reasonably priced, but a cow of a thing to swap over.

[The One]

Relay is cheap and easy.

Ignition switch is still reasonably priced, but a cow of a thing to swap over.

Yep. I'd be doing a relay first

[Lucas_R]

Interesting; a quick google suggests that Terminal 15 is all about ignition power, and the starter is on that circuit:

VWVortex.com - Relay Terminal 15 installed
Question Golf 1.6FSI Terminal 15 Relay
00576 - Terminal 15: Electrical Fault In Circuit - Advice Please - MkV (Mk5) Golf, Golf Plus & Jetta - uk-mkivs

That last link, although referring to different codes (still Terminal 15 related), does suggest the ignition switch may be to blame. I guess it's just one link in the chain though. Maybe the relay itself is the first place to look.

I had to replace the ignition switch on my Mk6 GTI about a year ago. Had different faults to what your car is showing though and the only sign that something was wrong was the RCD510 would turn on and off randomly while driving.

New ignition switch was $50 odd dollars from ECS Tuning. I can send you a link to the part if needed.

Changing it over is a bitch - airbag and steering wheel off, steering column trim off, then even more fun getting the switch out.

403 Forbidden

[AdamD]

Given the price and ease of replacement, sounds like replacing the relay first is the go.

I've spoken to the previous owner of the car - my dad - about the problem, and he tells me that this has been an intermittent problem with the car for many years. It sounds like it's becoming far more frequent now than in the past, but it's certainly not a new thing.

I cleared faults this evening and one (02403 - Terminal 15 for Interior: 012 - Electrical Fault in Circuit) came straight back before I tried to start the car. I wonder whether the reappearance of the code immediately points to the switch rather than the relay or anything else?

When I turned the key after scanning I got the 'click' and no start, but then a second turn of the key a couple of seconds later engaged the starter just fine.