A transmission fluid pressure switch/sensor is designed to monitor the hydraulic pressure inside of the transmission, then relay that data to the ECU so it can decide on a proper shift strategy for the situation. If there is an unusually high voltage on this switch’s circuit, a P0843 DTC will be set.
How Serious is the Code?
In terms of the seriousness, a P0843 diagnostic trouble code ranks pretty high. If there is an issue with the hydraulic pressure inside the transmission, or the transmission fluid pressure sensor that monitors it, a number of transmission problems can occur. And some of them may impact the drivability of your vehicle.
Symptoms of a P0843 include:
- Harsh, erratic shifts
- Transmission not able to shift gears
- Non-working torque converter clutch
- Transmission overheating
- Reduced fuel economy
- Low transmission fluid level
- Dirty transmission fluid / filter
- Transmission fluid leak
- Damaged wiring/connector
- Faulty transmission pump
- Torque convertor failure
- Transmission fluid pressure sensor failure
- Pressure control solenoid issues
- Pressure issues
- Valve body issue
- TCM failure
How to Diagnose the Code?
The first thing that should be checked when trying to diagnose a P0843 OBDII trouble code, is the level and condition of the transmission fluid. If everything looks good, then the condition of the wiring and connectors on the transmission wiring harness should be looked at. If no problems are found up to this point, then more in-depth mechanical diagnosis will be needed.
What Repairs Will Fix P0843?
- Change transmission fluid and filter
- Repair leaks
- Repair or replace damaged wiring and connectors
- Replace transmission fluid pressure sensor
- Repair or replace torque converter
- Repair or replace valve body
- Replace transmission pump
- Replace pressure control solenoid
- Replace pressure regulator
- Reprogram or replace TCM