OBD Codes List

Diagnostic reference · P0843

P0843

Transmission Fluid Pressure Sensor/Switch A Circuit High

System
Transmission (P code)
Lamp
Check Engine Light
Category
Powertrain - Transmission

What it means

P0843 means Transmission Fluid Pressure Sensor/Switch A Circuit High.

Where it lives

For P0843, the sensor sits on the circuit this code reports. The description of P0843 reports a fault at the sensor.

Check these first

  • An open in the sensor A return wire
  • A sensor A reading above the expected range
  • A stuck line pressure regulator valve
  • A signal wire shorted to voltage

What to do next

  1. Watch sensor A pressure on a scan tool
  2. Test the return wire for an open
  3. Test the signal wire for a short to voltage
  4. Check the line pressure regulator valve
  5. Replace sensor A if the value stays high
  6. Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.