Porsche 911 930 Oil Pressure Gauge pegging at max.

[ianfranc]

Just thought I would add my experience and solution with this issue as some of the previous threads on this subject did not cover my pain!.

Oil Pressure Gauge started to Peg at max with ignition on. The Gauge should only move slightly at this point. I started to considered an issue with the pressure Sender (engine mounted), rather than the gauge itself. Removed the gauge from the dash and plugged in long wires using spare male spade connectors into the wiring harness socket for the gauge. Battery on the car disconnected. Using a 12v light bulb as an indicator of current flowing and an off car spare battery.
Assumed as the gauge was pegging that there was current into the gauge, so the problem would be with a connection from the sender or the sender itself.. this assumption leaves only one wire to test. Green/Red.. i.e is it grounding via a short or just perhaps not in contact with the sender. Then if all is well, the sender will need to be checked next.
While attempting to make a circuit using the test bulb, the harness and the cable from the sender.. Nothing.. !.. Started to check the wire from the sender itself and found the circuit flickered for a moment.. carefully pulled off the black plastic connector which separates and found the wiring torn and damaged, barely held by the isolation tubing.
Repairing this connection was easier and cheaper than replacing this small part of the loom that also serves the oil temp gauge.
Replaced the harness connection into the gauge, repaired sender connection and reconnected all.. The gauge moved as it should with ignition on then started the engine. Back to normal..
One clear point to emphasise.. If the sender is not connected, the gauge goes up.... An electrician will probably add.. It works using resisitance in the circuit from the sender..
Happy not to be spending a small fortune on parts this time!.
Please don't shoot at me if I am stating the obvious to many, I am no expert.. Merely try to keep the costs of owning a classic to a minimum by having a go.!
Cheers all.

[PeteKz]

Ian, welcome to the forum. good to hear you found the problem with your gauge. Yes, it's a common problem and thanks for adding your experience and fix. At this age, many cars are having various electrical problems due to loose or corroded connections and broken wires due to vibration and flexing after 40 years of service, etc.

[917_Langheck]

Been there, done that....

https://forums.pelicanparts.com/porsche-911-technical-forum/1165388-how-do-you-fix-erratic-oil-pressure-sensor-sender.html

It's nice knowing the oil is running around inside the engine instead of streaming off into the distance while you're driving...