P0840 OBD II Trouble Code Transmission Fluid Pressure Sensor / Switch A Circuit

Symptoms of P0840 OBD II Trouble Code

  • Malfunction Indicator Light On
  • Change in shift quality
  • Vehicle starts off in 2nd or 3rd gear (limp in mode)

Common Causes of P0840 OBD II Trouble Code

  • Open in the signal circuit to the TFPS sensor - possible
  • Short to voltage in the signal circuit to the TFPS sensor - possible
  • Short to ground in the signal circuit to the TFPS sensor - possible
  • Failed TFPS Sensor ? likely Internal mechanical transmission issue - possible
  • Failed PCM - unlikely (programming required after replacement)

Severity of P0840 OBD II Trouble Code

Severity depends upon which circuit the failure has occurred in. Since this is an electrical failure, the PCM/TCM can compensate to some degree. The failure may mean that the PCM/TCM modifies the shifting of the transmission if electronically controlled.