Transmission Fluid Pressure Sensor

Monitors hydraulic pressure inside the transmission — the quantity that decides whether a clutch holds or slips, and the one the whole transmission code range keeps pointing at. Where a diagnosis says "have the line pressure measured with a gauge", this sensor is the vehicle doing that measurement for itself, which is why a pressure fault stored alongside a slipping or gear ratio complaint is corroboration rather than a second problem: it moves the diagnosis from worn clutches towards the pump, filter and valve body. Note that the standard covers both sensors and switches under one name and they are not equivalent — a switch reports only whether a threshold was crossed, a sensor reports a value, and only the second supports comparison against what was commanded. The critical caveat: a circuit reading low is not the same as pressure being low, and only a mechanical gauge on the test port distinguishes them, since every electronic reading arrives through the sensor under suspicion.

Also known as: line pressure sensor, tfp sensor, trans pressure switch, fluid pressure switch, pressure switch manifold, psm

Referenced by 70 codes

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Codes involving this component (70)

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