VW Golf GTi 1.8t 2001 petrol - VW Golf Emissions light on and off?

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Wed 2 Jun 2010 17:04
VW Golf GTi 1.8t 2001 petrol - VW Golf Emissions light on and off? - Laird Lugton

Over the past two years my Golfs exhaust emissions light has been on. When it first came on I took it to the VW dealer who looked at it, said they'd found a hose from the Secondary Air Pump which had almost come off so they put it back on and cleared the fault.

Within a day the light was back on. They suggested replacing the hoses to the pump so I went ahead at a cost of £80. Fault cleared and within a few days the light was back on.

Further investigation revealed the pump was broken (they alledged). Replacement cost was going to be upwards of £500. According to my Haynes manual the system is only used for 90 seconds on start up and it's job is to reduce emissions. Since MOT's are done on a warm engine I decided against replacement and two MOT's later it's still passing.

The code it would always throw up was P0411/16795 Secondary Air Injection System - Incorrect Flow detected. Once the Emissions Light was on it had to be cleared via the fault code reader. But I'd be able to drive for up to 2 weeks without it coming back on.

Recently I cleared the fault to see if I could determine the problem. I can hear the secondary air pump working as it emits a whine, shuts down after 90 or so seconds and then the revs drop to about 800rpm. However once the car is up to temp and been going for 10 minutes the emissions light comes on. Surely if the pump wasn't working the light would come on within the first 2 minutes?

Another interesting thing has happened whereby the light comes on 20 minutes into a drive and the next day the emissions light extinguishes itself.

This afternoon with the fault cleared by itself I hooked up my fault code reader and downloaded the following faults (no warning lights on dash showing)

16955 P0571 Brake Light Switch - implausible signal

17536 P1128 Fuel Trim; Bank 1 - system to lean

17705 P1297 Pressure Drop Between Turbo and Throttle Valve

Any ideas why my Exhaust Emissions Light has been coming on?

The car is only worth £3k and I'm about to sell it but don't want to sell on a duffer.

Many thanks.

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Wed 2 Jun 2010 21:59
VW Golf GTi 1.8t 2001 petrol - VW Golf Emissions light on and off? - elekie&a/c doctor

The fault codes you have here are probably in the top ten of Vag diagnostic problems.Continual brake light switch faults on these models never cease to amaze me and have changed them on cars barely 3 years old.As for the other 2 codes,these could be related to an air leak in the induction/turbo pipework or a fault with the pcv valve(crankcase vent system).Also may be worth cleaning the throttle body and plate and reset adaptions.hth

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Thu 3 Jun 2010 10:46
VW Golf GTi 1.8t 2001 petrol - VW Golf Emissions light on and off? - Laird Lugton

Thanks for the reply.

Any ideas why the exhaust emissions light would come on 10 to 20 minutes into a drive when the Secondary Air Pump is only used for 90 seconds on a cold start. Surely it would come on within the 90 seconds of the Secondary Air operation?

Thanks!

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Fri 9 Jul 2010 12:01
VW Golf GTi 1.8t 2001 petrol - VW Golf Emissions light on and off? - vwkirby83

hello way over from Winnipeg,Manitoba Canada I have been having the same problem about the air pump myself. my mechanic also said "dont worry about it, only used during enitial start". lol Im cheap so I have been driving along with a engine light on for over a year now. yes I have had it reset a couple times..and strangly at times it would light up like 5-20min after startup and drivearound. *shrugs* other than that, car runs like a champ. hitme back up at my e-mail vwkirby@hotmail.com

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