P0843: Transmission Fluid Pressure Sensor/Switch A Circuit High
What to do
If shifts have also become violent, the high reading may be real rather than an electrical fault. Ask for a mechanical gauge reading before parts are ordered — the sensor and the pressure are two different things and the code cannot tell you which is wrong.
What this code means
The pressure sensor circuit is reading above its valid range — an open circuit or a short to supply, which the module cannot separate.
The same caution as P0842 applies in the other direction: a circuit fault reading high and a transmission genuinely running at excessive pressure produce the same code, and only a mechanical gauge distinguishes them. Genuinely high line pressure is the less common of the two but not harmless — it makes every shift land hard and puts shock into the driveline, and it is what a pressure control solenoid stuck on will do.
Likely causes
Start here
- Open circuit in sensor wiring · moderate
- Corroded transmission connector · moderate
- Faulty transmission fluid pressure sensor · moderate
Less common
- Faulty pressure control solenoid · moderate
- Wiring shorted to voltage · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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