how to fix P0420 code on Ford Explorer Sixth Generation (2020-present)

Solution

1. Preparation

• Gather tools and materials: OBD-II scanner, multimeter, socket set, torque wrench, oxygen sensor socket, backpressure gauge, safety glasses, and gloves.
• Ensure the vehicle is parked on a level surface and the engine is cool.

2. Inspect and Replace Oxygen Sensors (if faulty)

• Step 1: Disconnect the battery negative terminal to prevent electrical shorts.
• Step 2: Locate the pre-catalytic converter oxygen sensor (usually near the engine) and the post-catalytic converter sensor (further down the exhaust).
• Step 3: Using an oxygen sensor socket, carefully remove the sensors. If they are difficult to remove, apply penetrating oil.
• Step 4: Install new oxygen sensors, ensuring they are properly torqued (usually around 30-40 lb-ft, check specifications).
• Step 5: Reconnect the battery terminal.

3. Inspect and Replace Catalytic Converter (if needed)

• Step 1: If the oxygen sensors are functioning properly, perform a backpressure test on the catalytic converter. If backpressure exceeds manufacturer specifications, the converter may be clogged.
• Step 2: Remove the exhaust system components as necessary to access the catalytic converter. This may include unbolting exhaust hangers and flanges.
• Step 3: Remove the old catalytic converter and install the new one, ensuring proper orientation and fit.
• Step 4: Reinstall any exhaust components and tighten to manufacturer torque specifications.

4. Clear Codes and Test Drive

• Step 1: Use the OBD-II scanner to clear the P0420 code from the vehicle's computer.
• Step 2: Start the engine and let it idle for a few minutes.
• Step 3: Take the vehicle for a test drive under various conditions (city and highway) to ensure the check engine light does not reappear.