MK5 Golf GTI
All Things Mk5 => Mk5 General Area => Topic started by: PhilNUK on December 21, 2016, 09:46:11 am
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Hi guys,
Had the yellow engine management light come on this morning on the way to work. Car is running fine from what I can tell.
I had a powervalve fitted with sports cat but that was about 8000 miles ago now.
Also got a revo intake.
It's standard map, does it just mean I need to get it mapped out? Why would it take so long to appear after installation?
I have a lot of driving to do later today and just need some assurances it will be OK to drive.
Thanks
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That is probably the 'catalyst efficiency' light. Very common when fitting sports cats or decats. It won't affect anything, so you're fine to keep using the car.
The rear lambda can indeed be mapped out. The front and rear lambdas have little chats with each other to make sure they both agree the fumes leaving the engine are satisfactory to German operating theatre standards. If the rear one disagrees with the front one, then on comes the EML light, but VW don't trim the fuelling or go into limp mode, it just throws the light and that's it, just to let you know you are killing Dolphins and Polar bears.
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thanks for the reply Pudding! I appreciate that...
Any reason why it would appear 8000 miles later? I have searched and a lot of posts show the light comes up after a few hundred miles normally. Could it be to do with the outside temp too?
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Maybe the cat has actually lost it's effectiveness. Aftermarket ones are nowhere near as good, or as long lasting as the factory ones. It's a gradual process.
On the factory exhaust, you can't tell if the front or rear cat is knackered because the rear lambda sits downstream of both of them, so visual inspection (or laser thermometer) is the only way to tell. But as your BCS cat is the only cat in the system, and your map is standard, it's the most likely answer I'm afraid. Occam's Razor and all that :smiley:
I have an APR downpipe. Expensive, and the sales pitch about their amazing "GESI" cat is laughable. In reality their cat is utterly useless. My car only just scraped through the MOT with 0.1 emissions. It should be 0.01, or zero. That's how it is with some aftermarket cats.
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thats interesting mate, thank you.. I have sent a mail to BCS to see what they say, but I guess the only sure way to solve it is to go R-Tech and go stage 2! Maybe wait for spring and put up with the light till then
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You can check it with a laser thermometer (cheap from Amazon). With the engine up to temperature, hold the revs at 2500rpm and the exit side of the cat should be considerably hotter than the input side. If not, it's knackered.
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To be honest it might not even be the cat - mine occasionally pops up if the runner flap motor stops working. Looking forward to doing a RFD over Christmas!
Best bet would be to vagcom it.
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Yeah best to get it scanned first as above!
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Could also be the P0441 EVAP code. Scan needed,
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Aye P0441 EVAP popped up on mine the other day, shortly after brimming the tank.
Cleared it, all good.
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I've had that too. Couldn't shift the code until I'd replaced the petrol cap, carbon can, the rigid line from carbon can to tank vent AND the N80 valve!!
Not a cheap fix, but the ECU doesn't do it's long term trims until the code is shifted.
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I have just ordered a scanner to get a code off the car... hopefully I don't end up on the hard shoulder on the m6 with my kids later!
cheers all
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If you have VCDS you can confirm it's the Lambda sensor & cancel the eml. When I fitted my BCS it went for about 1000 miles before EML first came in. then it would come back every 200 miles. I got lambda probe coded out when I had it mapped.
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My Powervalve was on for ages before it flagged the light up. 200 cell on R-Tech Stage 1 at the time.
Shortly after that it went for MOT and the emissions were excellent. I posted a photo of the test sheet up in a similar thread a couple of months ago. I'm sure @Pudding and @Shoduchi contributed to that thread, if you want to find it!
Don't worry about your cat.
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Got an error code checker thing and it came up with engine running too lean...