ATA 77

Faulty Engine Oil Temperature Transmitter Can Affect Oil Pressure Indication
If you are a Westwind owner-operator who is experiencing high oil pressure indication at altitude and have exhausted your troubleshooting skills, here is one more thing you may not have thought of.
Recently, a customer arrived with this scenario, ground runs were performed with redundant gauges to verify the oil pressure was correct. We noticed the complaint was valid only as an indication problem after the oil temprature started to rise. It was found that the oil temperature transmitter was faulty. The result was the oil pressure indication becoming erratic on the ground and reading high at altitude. The oil pressure and temperature are displayed in the same gauge, and apparently, one can influence the other. Replacing the oil temperature transmitter fixed the problem.