The ECU has to know how much hydraulic pressure is available, in order for it to decide on the best shift strategy. If there is a problem with the transmission fluid pressure sensor E circuit, then a P0989 DTC will be saved.
How Serious is the Code?
The P0989 diagnostic trouble code is extremely serious, and may result in a number of transmission problems like unusually abrupt shifts and limp mode.
Symptoms of a P0989 include:
- Harsh shifting
- Transmission will not go into gear
- Limp Mode
- Dirty transmission fluid
- Low transmission fluid level
- Damaged wiring
- Corroded/broken connectors
- Transmission fluid pressure sensor/transmission line pressure sensor has failed
- Valve body issues
How to Diagnose the Code?
When trying to diagnose a P0989 OBDII trouble code, it’s important to start by checking the level and condition of transmission fluid. Since low levels and dirt/sludge can reduce the overall transmission line pressure, dirty transmission fluid should be changed immediately. If that isn’t a problem, then the wiring and connectors along the transmission wiring harness will have to be closely inspected to see if there are any damage wires or corroded/broken connectors. If that isn’t an issue, then the TFPS switch will have the be tested. If it works properly, then there may be a mechanical problem that is triggering this OBD2 code (like valve body problems).
What Repairs Will Fix P0989?
- 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
- P0988 – Transmission Fluid Pressure Sensor/Switch “E” Circuit Range/Performance
- P0990 – Transmission Fluid Pressure Sensor/Switch “E” Circuit High.
- P0991 – Transmission Fluid Pressure Sensor/Switch “E” Circuit Intermittent