~my mk5 05 turbo loves 97 from total garage and is fine with any 95 standard petrol But.... if i load lets say one of the higher rating petrols like V-power or 98/99 my exhaust system dash light comes on. yes i've had the car looked at not'g vw soon as happened when happened, but nothing found. I did it again to test it out, and yes the light came on once again but I filled up with normal 95 and it cleared after about 50 miles so not really worried is there an underlying minor fault here? or am I bannished from using V-power and other vamped brands (unless I want a warning light) thanks if anyone can advise
I'll have a go... On another (non-VAG) forum I use, 'cat-efficiency' fault light and codes are a common occurrence on the models which have lambda sensors before and after the catalytic converter. One member has found that on his car, the warning light and associated codes seem to be triggered by changes in fuel composition, which the ECU can 'get over' given a chance. It happens each year when he goes abroad with the car, in both directions, as soon as he fills up with the 'new' fuel. His theory goes that the ECU monitors/learns some difference between the outputs of the before- and after-cat sensors, and then if this difference changes, it's assumed to be a problem with the cat performance, hence putting warning light on. He reckons that the change in fuel octane/composition between UK and French unleaded is enough to trigger this. I think he has some code-reader/scan tool that he uses to reset stuff and clear stored codes, and once he's done this the ECU is happy again until the fuel changes again when he changes country again. Might just be something similar going on with yours? Maybe.
thanks very interesting, I've since also been told that the light will eventually clear as the higher octane petrol is apparently clearing out something that normal petrol doesn't, and could cause some kind of blockage which will clear itself over time.?? could well quite be ball*hit but sounded good when told anyone?
yes it initially went straight to not'g vw for a plug in, but they said that even thou the light had been on it had since gone off, and no record of a fault found. weird..... but when i filled up again with v-power it happened again, so i quickly used it up and filled with normal 95- it eventually cleared... Hence never used again or any other high grade/octane petrol
