P0728 OBD II Trouble Code Engine Speed Input Circuit Intermittent

How to diagnose, repair, and info on causes of a P0728 engine code that means there is an intermittent fault in the engine speed input signal. Also includes links to relevant forum topics on the code.

Symptoms of P0728 OBD II Trouble Code

  • Erratic or inoperative speedometer/odometer
  • Automatic transmissions may shift harshly (limp-in mode)
  • Transmission fails to shift or shifts erratically
  • Inoperative or incorrect tachometer
  • Transmission slippage or delayed engagement
  • Additional transmission input/output speed codes may be stored

Common Causes of P0728 OBD II Trouble Code

  • Open or shorted wiring and/or connectors in the engine speed input circuit
  • Excessive metal deposits on the magnetic tip of the sensor
  • Defective engine speed input sensor or transmission output speed sensor
  • Damaged or worn engine speed sensor reluctor ring
  • Mechanical transmission failure which results in transmission/clutch slippage

Severity of P0728 OBD II Trouble Code

A stored code P0728 should be treated as severe due to the level of transmission damage and/or drivability issues that may result.