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?!
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.
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.
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.
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.
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.