My oil pressure gauge has started reading zero.

When I turn the ignition on the needle moves to the 0 mark but doesnt move when I crank over or the engine is running.

I have checked the sender with a volt meter and am getting millivolts or if i check with resistance it goes from around 10ohms from ignition on to around 70ohms running.

Is the sender meant to put out a voltage or does the resistance change with pressure? I know one will effect the other but what does the guage read?

Its a CAI smiths telemetrix oil gauge with a sender from CAI.

There is oil in the sump and nothing has really changed for the oil pressure to dissappear.

Sender reads in ohms.

The gauge then uses this to make a voltage change proportional to the oil pressure to move the gauge.

Sounds a little worrying...maybe try another gauge if the sender is working ok.

Any idea what sort of resistance change it should be for around 4 bar? I guess it depends on sender/gauge combo. As im getting a change in resistance I guess there is something happening there.

Ive got another sender but not another gauge to hand.

Depends on the sender, is it a VDO type? If so they are 10-180ohms

10 at 0 bar

180 at 5 or 10 bar depending on the sender.

fit the other sender and test the out put from that one. If they are the sam I would hazard a guess that the gauge is at fault

It came with the gauges from europa, but it is the same as

REVOTEC OIL PRESSURE SENDER 1/8NPT



[Edited on 30/10/2009 by greggors84]

I have telemetrix gauges and recently fitted a pressure gauge.

The sender provides resistance to the gauge. If the sender is not connected or not grounded correctly the needle will go to the max reading and stay there.

So my thoughts - check the wiring (particularly the grounds) then disconnect the wire from the sender with the power on - if the needle shoots up then the gauge is fine...if it stays at zero I'd suspect the gauge is at fault.