The ECU is constantly receiving electrical signals from the transmission fluid pressure sensor, which tell it how much hydraulic pressure there is to work with. If the TFPS sensor is not performing the way it is supposed to, a P0988 DTC will be triggered.
How Serious is the Code?
A P0988 diagnostic trouble code is extremely serious, and can result in a number of transmission problems that include unusually harsh gear changes and failed gear engagement.
Symptoms of a P0988 include:
- Harsh shifts
- Failed gear engagement
- Limp Mode
- Low or dirty transmission fluid
- Damaged wiring and/or connectors
- Faulty transmission line pressure sensor/transmission fluid pressure sensor
- Valve body issues
How to Diagnose the Code?
When a technician goes to diagnose a P0988 OBDII code, they should start by checking the level and condition of the transmission fluid. Low or dirty transmission fluid can use the hydraulic pressure inside the transmission and trigger this code. If no issues are found with the ATF, then the wiring and connectors along the transmission wiring harness thoroughly examined for signs of damage wires, and broken or corroded connectors. After that, the transmission line pressure sensor will need to be tested. If it works properly, then the problem may be mechanical in nature, like problems with the valve body or transmission pump.
What Repairs Will Fix P0988?
- Add or change transmission fluid and filter
- Repair or replace damaged wiring and connectors
- Replace transmission fluid pressure sensor/switch
- Repair or install remanufactured valve body
- P0987 – Transmission Fluid Pressure Sensor/Switch “E” Circuit
- P0989 – Transmission Fluid Pressure Sensor/Switch “E” Circuit Low
- P0990 – Transmission Fluid Pressure Sensor/Switch “E” Circuit High.
- P0991 – Transmission Fluid Pressure Sensor/Switch “E” Circuit Intermittent