Capteur de pression d'huile défectueux

The sensor or switch reporting oil pressure, which is worth separating from the pressure itself because the consequences of getting the two the wrong way round are asymmetric. Treating a real pressure loss as a sensor fault destroys the engine; treating a sensor fault as a pressure loss costs a part and an afternoon.

So the rule is to disprove the pressure first, not the sensor. Fit a mechanical gauge. If pressure is genuinely correct across idle, load and full temperature, the sensor or its circuit is at fault and can be replaced with confidence. Until that measurement exists, a low reading is a low pressure, however plausible a sensor fault seems.

When it is the sensor, the failure is usually its environment rather than its element. It is threaded into the block, so it sees heat and vibration continuously, and its connector sits where oil mist and road spray collect. Corrosion in the plug and oil wicking into the connector account for a large share — the second of which will also travel the harness. Note that many engines use a simple switch rather than a sensor, which can only report above or below one threshold and cannot show a pressure that is merely marginal.