Hello,

I've fitted a new Racetech OP gauge and sender to my car, but as soon as I turn the ignition on the gauge goes round to max, and stays there when the engine is started. If I disconnect the sender the gauge drops down to zero.

The sender is in a t-piece with the OP light and this works fine.

Any suggestions?

Cheers, James

sounds like a faulty sender to me
had it stayed at max with the wires off then i would suspect a short circuit but as it drops with the wire off the i would go with a faulty sender unit

Wired wrong way around? does the sender have 2 wires? check resistance of sender if it is a dead short then it is duff, if it doesn't change when engine is running it is still duff!

Caber

Where is the oil sender screwed into?

If its into a remote filter head, you need to ground the filter head/sender (presuming its a single wire sender).

Either way, check you've got zero resistance between sender body and engine/chassis earth. Using ptfe tape etc, can cause this issue as there's no continuity hence reads max pressure.