Golf emissions warning light | Technical matters | Back Room Forum

Sat 4 Nov 2006 11:38

Golf emissions warning light - Chips with everything

My Mother in law has a VW Golf which has just started showing the emissions warning light. The car has just had a new exhaust as the catalytic converter was apparently 'shot' and the warning light only appeared after this was done.

Naturally she is worried has to whether the car is going to let her down, particularly if she has any of the Grandchildren in it.

The garage that did this have run a full diagnostic on the car and maintain there's nothing wrong with the car.

She's taken it to VW, who have also run a full diagnostic on the car and they confirm that all is well.

What's the purpose of this light, is it to signify that there's something wrong with the car or simply to indicate the car may be contributing to the Planets demise more than usual?!

Thanks in advance,

CWE.

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Sat 4 Nov 2006 13:03

Golf emissions warning light - Aprilia

She's taken it to VW, who have also run a full

diagnostic on the car and they confirm that all is well.

Strange! If the light is on then there is a problem. It could be as simple as the oil filler cap is loose, or something more involved (e.g. shot lambda sensor). If there is nothing wrong then the VW dealer should have cleared the fault code, putting the light off.

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Sat 4 Nov 2006 20:13

Golf emissions warning light - Chips with everything

Thanks Aprilla.

The lights appearance is intermittent, however it was evident at the VW garage - apparently.

I'll check the oil filler cap - that's (shamefully!) about the limit of my car maintenance skills.

I seem to recall MIL saying that VW had given the lambda sensor the all clear, but I may be mistaken. Again, I'll check it out.

Many thanks,

CWE.

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Sun 5 Nov 2006 09:21

Golf emissions warning light - braindead

it sounds as if the lambda wiring is suspect thro being disturbed

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Sun 5 Nov 2006 10:08

Golf emissions warning light - Peter D

Yep that's where I would first go but it should have logged a fault code. How long does the light stay on for and are there any particular condition that cause it to come on. Regards Peter

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Tue 14 Nov 2006 11:27

Golf emissions warning light - Chips with everything

Apologies for the delay in responding - I've just changed ISP!

The light stays on "for about a week" and then stays off for a similar time. In addition the lambda valve has been changed, incurring significant expense.

Regards,

CWE.

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Tue 14 Nov 2006 12:18

Golf emissions warning light - Screwloose

Chips

Nothing's making sense here; so let's have the full details.

Golf Mk ?? Engine size [and three-letter code from inside handbook cover if available.] Year of reg. Why was the cat considered "shot" and how was this discovered? Why was the [whole?] exhaust changed and not just the cat?

If the MIL light has been on for more than a few seconds, a fault-code should be permanently stored in the engine ECU's fault memory: alerting you to the presence of a code is that light's main function. [VW's are usually very good at this: French manufacturers please note!]

Don't throw any more parts at it until the light/code issue is resolved. There are literally thousands of possible codes; guessing is not an option.

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Tue 14 Nov 2006 14:11

Golf emissions warning light - jc2

The light should not come on for an oil filler cap but can for a fuel filler cap as this would show evaporative emission system not working.

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Fri 24 Nov 2006 17:54

Golf emissions warning light - Chips with everything

The Golf is an X reg - so mk4 (I think) with 1.6 under the bonnet.

From what I understand (being a third party to all of this!) is that the exhaust needed replacing probably due to lots of short runs leading to water cumulating in the exhaust system.

The emissions light stays on "for about a week" and then goes off again "for about a week", so as you say a fault code should be present in the ECU - but apparently not. Mmmmm....

No more money will be spent on the car, especially now that other lights have started appearing - the boot open light being one of them!

To be honest, the prospect of disabling the light(s) and selling the car is not a wholly unrealistic situation.

Thanks to you and everyone else for the assistance,

Cheers,

CWE.

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Tue 5 Dec 2006 18:58

Golf emissions warning light - yogi69

Hi a common fault that can bring the light on is the 4 pin green temp switch, this sends signals to and from the ecu but not just for water temp, hope that helps. By the way its only about £19 or so so if your still trying to get the light out then its a cheap shot.

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Tue 5 Dec 2006 22:49

Golf emissions warning light - Screwloose

Chips

Sorry; I missed your response when it was posted. So the cat was replaced due to "accumulated water from short runs?" For something that runs at near red heat in a stainless-steel casing, that's a new one! [A tailpipe - maybe. A cat - never. That gem didn't come from one of those quick-fit exhaust places, did it? Did they also try and sell you four shocks and a set of brakes too?]

The fault-code logging system on any Golf that late would store a code, virtually forever, if the MIL light had been on. It's possible the codes had just been wiped and had not yet recurred when the dealer looked for them. Find some other diagnostic specialist [ask at your local motor factors etc.] and have the ECU [and now the instrument] codes read. Then get them to check under EOBD protocols; there may be other codes [and useful "pending codes"] stored in that side of the ECU too.

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Mon 3 May 2010 11:16

Golf emissions warning light - rfm943

My wife has a 56 Reg Golf Plus TDI 105 Luna and we have the same problem.

We took it to our local independent VW specialist in Leeds who diagnosed a faulty EGR valve when he ran the diagnostics. This was replaced (about £150) but the light came back on the next day. Back to the garage who ran the software again.

The mechanic had a look and said that it appeared that the Box 17 was not maintaining the correct pressure and so this was replaced as well (another £150).

The light came back on again the day after so I am not sure where to go from here. My wife thinks that the car is really down on power and that she has her foot down to the floor and has difficulty getting over 70 mph.

Very frustrated - we could take into into the VW dealer but he will charge £50 just for plugging the diagnostics in.

As a matter of interest the car does spend most of its time doing short runs with a lot of stopping and starting. When we took it in the first time the garage said that we could consider putting in a fuel additive and then running it at high revs for an extended period. Any ideas would be welcome.

Edited by rfm943 on 03/05/2010 at 11:17

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