P0872Powertrain
Powertrain · SAE
Transmission Fluid Pressure Sensor/Switch C Low
Meaning
The transmission control module has detected that the transmission fluid pressure sensor/switch C signal is below the lower specification limit. The sensor circuit is producing a voltage signal that is too low, or actual pressure in circuit C is insufficient.
Common causes
- Faulty pressure sensor/switch C with signal voltage outside specification
- Short to ground in the sensor C signal wire
- Partial open circuit or high resistance in the sensor C wiring
- Actually low hydraulic pressure in transmission circuit C
- Oxidised connectors increasing resistance in the signal circuit
- Internal TCM fault
Symptoms
- Check engine or transmission warning light on
- Abnormal gear shifts or insufficient pressure in circuit C-controlled gears
- Transmission in limp mode
- Slipping under certain driving conditions
Severity
High: a low pressure signal can prevent the TCM from applying the correct pressure, causing clutch slippage and transmission damage.
What to do
- Check ATF level and condition
- Measure sensor C signal voltage with a multimeter (check reference voltage and output voltage)
- Check wiring for shorts to ground or high resistance
- Measure actual hydraulic pressure in circuit C with a gauge to determine if the fault is mechanical or electrical
- Replace pressure sensor/switch C if signal is outside specification