In order to move the gears and clutches around inside of your transmission, there needs to be a certain amount of hydraulic pressure inside the transmission at all times. The transmission fluid pressure sensor constantly monitors the hydraulic pressure, then relays this data to the ECU through an electrical voltage signal. A P0874 DTC gets triggered if this signal becomes intermittent.
How Serious is the Code?
In terms of seriousness, a P0874 diagnostic trouble code ranks pretty high because it could be caused by either a failed sensor or mechanical failure inside the transmission (often the transmission pump or valve body).
Symptoms of a P0874 include:
- Overheated transmission
- Transmission will not engage a gear
- Transmission fluid should be refilled
- Dirt/sludge in the transmission fluid
- Transmission fluid is leaking
- Transmission overheats
- Engine overheats
- Damaged wiring
- Broken/corroded connectors
- Faulty transmission pump
- Faulty transmission fluid pressure sensor
- Faulty transmission fluid temperature sensor
- Faulty TCM
- Internal mechanical failure
How to Diagnose the Code?
When a technician goes to diagnose a P0874 OBDII trouble code, they should start by checking the manufacturer’s TSB database to see if there are any known fixes for these transmission problems. Next, they should check the wiring and connectors going to the TFPS sensor, to see if there are any frayed wires or corroded/broken connectors. This sensor itself should also be checked to make sure that it works properly. If there are no problems found up to this point, then an internal mechanical failure should be suspected.
What Repairs Will Fix P0874?
- 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