A vehicle’s ECU needs to know how much hydraulic pressure is available inside the transmission, that way it knows what’s going on and how it should set the shift pattern. The P0873 DTC gets saved if the voltage signal coming from the transmission fluid pressure sensor is too high, which could indicate a sensor failure or a mechanical failure inside the transmission.
How Serious is the Code?
The P0873 diagnostic trouble code is one of the more serious DTC’s, because it could be caused by either a mechanical problem with the valve body or transmission pump. But it could also be caused by a failed sensor or wiring issue. In either case, expect a number of drivability issues.
Symptoms of a P0873 include:
- The transmission is overheated
- Transmission is slipping in-and-out of gear
- Failed forward or reverse gear engagement
- The transmission fluid is below acceptable levels
- Transmission fluid needs to be changed
- Transmission fluid leaks
- Transmission overheated
- Engine overheating
- Damage to the wiring or connectors
- Failed transmission pump
- Failed transmission fluid pressure sensor
- Failed transmission fluid temperature sensor
- Failed TCM
- Internal mechanical failure
How to Diagnose the Code?
When trying to diagnose a P0873 OBDII trouble code, the manufacturer’s database of TSB’s should be checked to see if there are any known solutions. The wiring and connectors leading to the TFPS sensor should be checked for signs of damage, and the sensor itself will need to be tested to see if it’s working. If everything up to this point is in good order, then an internal mechanical failure should be expected.
What Repairs Will Fix P0873?
- 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