Faulty transmission fluid pressure sensor or switch 'C'; Damaged or corroded wiring in the sensor circuit, such as a short to ground; Loose or contaminated electrical connector at the sensor; Low transmission fluid level or degraded fluid causing actual low pressure; Internal transmission hydraulic issues, such as a stuck valve or worn pump; A malfunctioning transmission control module (TCM) or poor ground connection

DTC codes / P08xx · Transmission / P0872

P0872Transmission Fluid Pressure Sensor/Switch 'C' Circuit Low

Q: What does code P0872 mean?

Transmission Fluid Pressure Sensor/Switch 'C' Circuit Low. P0872 indicates that the transmission control module (TCM) has detected an abnormally low voltage signal on the circuit for transmission fluid pressure sensor or switch 'C'. This sensor monitors hydraulic pressure inside the transmission, and a low signal can mean the circuit is shorted to ground, the sensor has failed, or actual fluid pressure is lower than expected.

P0872 indicates that the transmission control module (TCM) has detected an abnormally low voltage signal on the circuit for transmission fluid pressure sensor or switch 'C'. This sensor monitors hydraulic pressure inside the transmission, and a low signal can mean the circuit is shorted to ground, the sensor has failed, or actual fluid pressure is lower than expected.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaTransmission

Symptoms you may notice

Illumination of the check engine light or transmission warning light, often with no other noticeable symptoms
Harsh or delayed shifting, especially when the transmission is cold or under load
The transmission may enter limp mode, limiting vehicle speed and gear selection
Slipping between gears or failure to engage certain gears
Poor fuel economy or unusual engine RPM fluctuations during acceleration

Common causes, most likely first

Faulty transmission fluid pressure sensor or switch 'C'
Damaged or corroded wiring in the sensor circuit, such as a short to ground
Loose or contaminated electrical connector at the sensor
Low transmission fluid level or degraded fluid causing actual low pressure
Internal transmission hydraulic issues, such as a stuck valve or worn pump
A malfunctioning transmission control module (TCM) or poor ground connection

How to diagnose and fix it

Check transmission fluid level and condition; top off or replace fluid if necessary
Inspect the sensor 'C' electrical connector and wiring for damage, corrosion, or loose pins
Test the sensor 'C' circuit with a multimeter to verify voltage and resistance against manufacturer specifications
Replace the transmission fluid pressure sensor or switch 'C' if testing indicates it is faulty
Repair or replace damaged wiring or connectors in the sensor circuit
Clear the diagnostic trouble code and perform a road test to verify the repair
If the code persists, diagnose internal transmission hydraulic pressure issues or the TCM

What P0872 Often Misleads You About

A low signal at sensor 'C' frequently results from a short to ground in the wiring harness rather than a failed sensor, so always inspect the harness before replacing parts.
Low transmission fluid pressure can be caused by a clogged filter or degraded fluid, which may set this code without any sensor fault at all.
Some vehicles use sensor 'C' for a specific pressure circuit, such as line pressure or clutch pressure, and a code for one sensor does not always indicate a global transmission failure.
Intermittent connections at the sensor can set P0872 only under certain conditions like temperature changes or vibration, making it hard to reproduce during a quick test.
A faulty ground connection for the TCM or sensor circuit can mimic a low signal and is often overlooked during diagnosis.

Can I keep driving with P0872?

It is generally safe to drive short distances to a repair shop, but avoid heavy acceleration or towing, and be prepared for the transmission to enter limp mode. Continued driving with low fluid pressure can cause internal damage, so schedule diagnosis promptly.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.