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2020 FORD F-150
5.0L V8 Coyote•RWD•AUTOMATIC•gas
11 active safety recalls on this vehicle — view recalls
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Repairs420Labor1001Torque8720Fluid18DTC3214Battery2Maintenance0Recalls11
P0126moderate severityPowertrain

Insufficient Coolant Temperature for Stable Operation

on 2020 Ford F-150 5.0L V8 Coyote · RWD

What this code means

The engine is not reaching or holding a stable operating temperature. This is often caused by a thermostat stuck open.

Symptoms

  • Poor heater output
  • Poor fuel economy
  • Longer warm-up time

Common causes

  • Thermostat stuck open
  • Faulty engine coolant temperature sensor
  • Low coolant level
  • Faulty cooling fan running constantly

Diagnostic steps

  1. Monitor coolant temperature at warm-up
  2. Inspect thermostat operation
  3. Test coolant temperature sensor
  4. Replace thermostat or sensor as needed
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