P0843 — Transmission Fluid Pressure Sensor/Switch A Circuit High

P0843: Transmission Fluid Pressure Sensor/Switch A Circuit High — what it means, the affected system and what to check before replacing parts.

Meaning, symptoms, causes and checks

Transmission Fluid Pressure Sensor/Switch A Circuit High. Basic catalogue definition; diagnostic details have not yet been reviewed.

Affected system: Powertrain

Symptoms

  • The transmission may log an abnormal A fluid-pressure sensor/switch signal (above the expected electrical range).
  • A warning and harsh, delayed or restricted gear changes are possible; some vehicles show little change.

Possible causes

  • A shorted signal wire, connector damage or a defective pressure sensor can produce an electrical level fault.
  • A high or low circuit signal does not by itself prove that the actual transmission oil pressure is high or low.

What to check

  • Confirm the fault and read the pressure-sensor signal and related transmission codes.
  • Inspect the sensor connector and wiring; measure reference supply, ground and signal using the vehicle circuit diagram before replacing the sensor.

Also written as: P0843-00, P084300, PO843 (some scan tools add the fault-type byte, e.g. -00).