2005 GTI..story so far. About 4 weeks ago she went in for an MOT and the Exhaust Emissions light on problem to fix. MOT no probs, they came back saying that the light was on because of a faulty inlet manifold runner control. I had noticed a slight loss in power and a sort of "push/pull" feeling every so often. Today the car went in to have the part changed at a cost of £300 inc labour and I was told that another fault had "appeared". This time it was 05853 P2187 bank 1 fuel measuring system too lean at idle. They said that it is a malfunction due to a malfunction of the non-return valve in the pressure control valve at the front of the cylinder head. The light they added had gone out but may come on again due to this new fault. Is it a lengthy and expensive job to do? Will I notice any difference if I dont do anything just yet with no light on? Is this new fault anything to do with the Diverter Valve (I had them check what version and condition, it is a version C and the diaphragm was fine). Thoughts appreciated fella's.