The transmission fluid pressure sensor is designed to tell the ECU what the current operating pressure is inside of the transmission. If a P0871 DTC is stored, it means that the voltage signal coming from the sensor falls outside of the normal operating parameters.
How Serious is the Code?
The P0871 diagnostic trouble code is actually fairly serious, as it relates to the hydraulic pressure needed to operate the transmission. If this sensor is failing or has detected a pressure problem, you will experience a number of drivability issues.
Symptoms of a P0871 include:
- Transmission overheating
- Failed gear engagement
- Low transmission fluid level
- Dirty transmission fluid
- Transmission fluid leak
- Overheated transmission
- Overheated engine
- Damaged wiring and connectors
- Transmission pump failure
- Transmission fluid pressure sensor failure
- Transmission fluid temperature sensor failure
- Transmission control module failure
- Internal mechanical failure
How to Diagnose the Code?
One of the first steps to diagnosing a P0871 OBDII trouble code, is to check the manufacturer’s TSB database to see if there are any known solutions for this transmission problem. Next, the wiring and connectors leading to the TFPS sensor need to be inspected for signs of damage and corrosion. The transmission fluid pressure sensor will need to be tested as well, to determine if it is operating properly. If no issues are found up to this point, then an internal mechanical issue (most likely in the valve body) should be suspected.
What Repairs Will Fix P0871?
- Change the transmission fluid and filter
- Repair transmission fluid leaks
- Repair or replace damaged wiring and sensors on the transmission wiring harness
- Replace the transmission pump
- Replace transmission fluid pressure sensor
- Replace transmission fluid temperature sensor
- Replace or repair valve body
- Replace or repair transmission