My oil light stays on at about 75% brightness (and flickers a bit) after starting. I just used a pressure washer to clean under the hood, so I thought that maybe some wires were shorting, however if I disconnect the wire at the oil pressure switch, the light never comes on.

If I attach an ohmmeter to the switch and read resistance to ground, I get a short when the engine's off, and about 12k after starting. I'm wondering if:

A) some water got into the switch that is providing a 12k path to the grounded casing of the switch

B) the switch is failing, so that even when proper oil pressure is reached, the switch never acheives a true open circuit

C) proper oil pressure isn't being reached, hence the resistance it reads is between a short and an open circuit.


If A) is the case, I'll find out soon enough when it's had a chance to dry out.

If drying out doesn't help, and B) is a plausible explanation, then I'll drive the car until I can get another switch, but if C) is a more likely explanation, I should park the car until I can replace the switch (to eliminate the switch as the possible source of the problem), and re-diagnose from that point.

I'd appreciate anyone's opinions on whether any or all of these explanations are believable interpretations of what is happening.