how to fix P0420 code on Ford Explorer Fifth Generation (2011-2019)

Ford Explorer Fifth Generation (2011-2019)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

Error Code: P0420

3 min read

594 words

Problem Statement

Learn how to diagnose and fix P0420 exhaust system issue in Ford Explorer (2011-2019). Step-by-step guide with diagnostic procedures and repair instructions.

Error Code

P0420

Affected Component

Exhaust System

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect battery before working on electrical systems.
•Allow engine to cool before opening exhaust system.

Symptoms

•Check engine light illuminated
•Decreased fuel efficiency
•Rough engine performance or misfires
•Sulfur smell from exhaust
•Failed emissions test

Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to confirm P0420.
2
Inspect the exhaust system for any visible leaks or damage.
3
Check the operation of the upstream and downstream oxygen sensors using a multimeter.
4
Measure the temperature differential between the inlet and outlet of the catalytic converter.
5
Verify that the engine is running at the correct temperature and that there are no coolant leaks affecting performance.

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•OBD-II scanner
•Oxygen sensor socket
•Torque wrench
•Multimeter
•Infrared thermometer

Parts Required

•Upstream oxygen sensor
•Downstream oxygen sensor
•Catalytic converter (if needed)
•Anti-seize compound

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Diagnostic Steps

1
Scan for error codes using an OBD-II scanner to confirm P0420.
2
Inspect the exhaust system for any visible leaks or damage.
3
Check the operation of the upstream and downstream oxygen sensors using a multimeter.
4
Measure the temperature differential between the inlet and outlet of the catalytic converter.
5
Verify that the engine is running at the correct temperature and that there are no coolant leaks affecting performance.

Solution

1. Preparation

Gather necessary tools and parts.
Ensure the vehicle is parked on a level surface and the engine is cooled down.
Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Replace Oxygen Sensors

Locate Oxygen Sensors: Identify the upstream (pre-catalytic converter) and downstream (post-catalytic converter) oxygen sensors.
Remove Sensors:
- Use an oxygen sensor socket to unscrew the sensors from the exhaust manifold and catalytic converter.
- Be careful to avoid damaging the wiring.
Install New Sensors:
- Apply anti-seize compound to the threads of the new sensors.
- Thread the new sensors into place and torque to the manufacturer’s specifications (typically around 30 lb-ft).
Reconnect Wiring: Ensure electrical connectors are secure.

3. Inspect and Replace Catalytic Converter (if necessary)

Visual Inspection: Check for any physical damage or signs of excessive heat on the catalytic converter.
Temperature Test: Start the engine and let it reach operating temperature. Use an infrared thermometer to compare inlet and outlet temperatures; a significant difference indicates a clogged converter.
Remove Old Catalytic Converter:
- Loosen and remove the bolts connecting the catalytic converter to the exhaust.
- Carefully detach the converter from the exhaust system.
Install New Catalytic Converter:
- Position the new catalytic converter and secure it with bolts.
- Torque bolts to manufacturer specifications (consult repair manual for exact values).

4. Clear Codes and Test Drive

Reconnect Battery: Reconnect the negative battery terminal.
Clear codes: Use the OBD-II scanner to clear the P0420 code.
Test Drive: Drive the vehicle under various conditions to ensure the check engine light does not return.