Thanks for the replys guys.

Kjc300 - Cheers for the diagram mate but it goes straight over my head, if i knew the colours of the wires and where they go in/out of the fusebox then id probably be able to check them.

escossie - I already checked the yellow relay and replaced it with 3 others but still no joy, im also a live on one of the pins, but thanks for the advice mate.

Forgot to mention that both the boost and oil pressure gauges work fine, so it might be the gauge itself. Paid £300 for a brand new fusebox in the hope this would sort out my electrical problems.

Anymore help would be gratefully appreciated,

Thanks, Lee