how to diagnose a P0128 code on my Ford F-150

Learn how to diagnose and fix P0128 code in Ford F-150. Step-by-step guide with symptoms, diagnostic steps, tools, and repair instructions.

Solution

1. Preparation

• Gather tools and materials needed for repair.
• Disconnect the battery to ensure safety while working on electrical components.

2. Coolant Inspection

• Sub-steps:
  • Check the coolant level and top off if needed with the specified coolant type (Ford Gold or equivalent).
  • Inspect the condition of the coolant for contamination or rust.
• Tools Required: Coolant tester, funnel.

3. Thermostat Replacement

• Sub-steps:
  • Drain the coolant from the radiator until it is below the thermostat level.
  • Remove the thermostat housing by unscrewing the bolts (use a torque wrench to avoid over-tightening).
  • Take out the old thermostat and inspect it for proper operation (it should open when heated).
  • Install the new thermostat ensuring the gasket is in place and torqued to manufacturer specifications.
• Tools Required: Socket set, torque wrench, gasket scraper.

4. ECT Sensor Testing

• Sub-steps:
  • Disconnect the ECT sensor connector.
  • Using a multimeter, check the resistance of the ECT sensor at various temperatures (refer to the service manual for specific resistance values).
  • If the values are outside specifications, replace the sensor.
• Tools Required: Multimeter.

5. Reassemble and Refill

• Sub-steps:
  • Reconnect the battery.
  • Refill the coolant system with the correct type and mixture.
  • Bleed the cooling system to remove any air pockets.
• Tools Required: Funnel, coolant flush kit (if needed).