P0840: Transmission Fluid Pressure Sensor/Switch A Circuit
MediumPowertrainTransmission
What does P0840 mean?
P0840 is a diagnostic trouble code indicating "Transmission Fluid Pressure Sensor/Switch A Circuit". A sensor in the transmission is reporting abnormal data or has lost communication with the ECU. Sensors can fail due to age, contamination, heat exposure, or wiring issues.
Common causes
- Low or degraded transmission fluid
- Worn clutch packs or bands
- Faulty shift solenoid
- Wiring issue to the transmission control module
- Failing torque converter
What should you do?
Schedule a diagnostic appointment at your earliest convenience. The vehicle is generally safe to drive short distances, but the underlying issue should be addressed to prevent it from worsening.
Get a diagnosis for YOUR car
Code P0840 can mean different things depending on your vehicle. TorqueBot gives you a diagnosis specific to your make, model, and year.