Error code

OBD2 P0840

OBD2P0840
Diagnostic Trouble Code· Standard OBD-II fault code read from the vehicle's onboard diagnostics.

What it means

Transmission Fluid Pressure Sensor/Switch 'A' Circuit.

Severity

moderateCan drive, but may experience shifting issues and reduced transmission performance.

Summary

P0840 indicates a malfunction in the transmission fluid pressure (TFP) sensor A circuit, which monitors the hydraulic pressure within the transmission.

Common Causes

  • Poor wiring or connection
  • Faulty TFP sensor
  • ECM/PCM/TCM issue

Fixes

  • Replace the faulty TFP sensor or repair wiring connections.
View source

Not affiliated with OBD2. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.

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