P0126 OBD II Trouble Code Insufficient Coolant Temperature for Stable Operation

Symptoms of P0126 OBD II Trouble Code

  • Low engine coolant level
  • Faulty thermostat
  • Faulty coolant temperature sensor (CTS)
  • CTS electrical wiring or connector problem - open, short, or poor connection

Common Causes of P0126 OBD II Trouble Code

  • Check to ensure proper cooling fan operation. On when it should be on, off when it should be off, repair as necessary. If the cooling fan is always on, it could be causing the engine to warm up too slowly or not warm up to proper operating temperature.
  • Check engine coolant level. If low, top up, clear code and drive vehicle to see if it returns.
  • Refer to the "freeze frame" data and view live data using a code scanner to see the value of the engine temperature sensor. Compare with manufacturers specifications.
  • Use a laser thermometer to verify the temperature of the coolant as close as safe, measure the temperature of the engine and compare with the value of the sensor reading.
  • Inspect for a faulty thermostat, coolant temperature sensor (CTS), and wiring. Repair as required.