what does it mean if my Ford F-150 Fourteenth Generation (2021-present) shows error code U0420

Learn how to diagnose and fix U0420 electrical issue in Ford F-150. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather necessary tools and ensure the vehicle is parked on a level surface.
• Disconnect the vehicle’s battery to prevent electrical shorts.
• Tools required: OBD-II scanner, multimeter, socket set.

2. Inspect Wiring and Connectors

• Remove the vehicle speed control module located under the dashboard or near the engine compartment, as specified in the service manual.
• Visually inspect the wiring harness and connectors for signs of wear, corrosion, or damage.
• If damage is found, repair or replace the affected wiring or connectors.

3. Check Power and Ground

• Reconnect the battery and turn the ignition on without starting the engine.
• Using a multimeter, check for voltage at the vehicle speed control module's power supply line; it should read approximately 12 volts.
• Verify the ground connection using the multimeter; there should be continuity to chassis ground.

4. Replace the Vehicle Speed Control Module (if necessary)

• If power and ground are good, but the error persists, replace the vehicle speed control module.
• Disconnect the module's connectors and remove it from its mounting.
• Install the new module, ensuring all connectors are secure and properly seated.

5. Recheck the System

• Reconnect the battery, clear any DTCs using the OBD-II scanner, and perform a road test.
• Monitor the system for any reoccurred codes or symptoms.