Hi to all A4 gurus......

The emission control warning light comes on occasionally on my car, which is a 54 plate A4 2.0T FSi Quattro. I have noticed that the mpg drops off by on average 4 to 5 mpg when this happens.

Today I took the car out on a run. When I set out the light was on and according to the computer the car was doing only around 30mpg at 70mph in 6th. After some miles the mpg indication rose steadily to around 37mpg at 70mph, though the light stayed on (I assume it does not reset until the ignition is switched off). On the return journey the light was off and stayed off.

Having only had the car a month or so, I'm not 100% certain whether there is a loss of power when the light is on - perhaps power does decrease a little, but I rarely use anything like the BHP available.

A couple of weeks ago my garage diagnosed the problem as low fuel pressure, but were unable to locate the actual source of the problem as it is intermittent.

There is one other issue I have - trying to get petrol into the tank. The petrol pump keeps switching off and it takes an age to get the tank filled. Is this a general issue with A4's (I never had any problem with my last car, an A6) or is the tank vent likely to be blocked?

Any advice would be appreciated.

TIA.