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

high

Severity

Error Code: P0420

3 min read

597 words

⚠️ Safety Warning

This issue requires immediate attention. If you are not experienced with automotive repairs, consult a professional mechanic. Working on critical systems can be dangerous.

Problem Statement

Learn how to diagnose and fix P0420 catalytic converter issues 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 the battery before working on electrical systems.
•Allow the exhaust system to cool before handling any components.

Symptoms

•Check engine light illuminated
•Decreased fuel efficiency
•Rough idle or engine misfire
•Failed emissions test
•Increased engine noise (if catalytic converter is damaged)
•Unusual smells from exhaust (if converter is damaged)

Diagnostic Steps

1
Scan the vehicle’s computer system using an OBD-II scanner to confirm the P0420 code and check for any additional codes.
2
Inspect the exhaust system visually for any signs of damage, leaks, or loose connections.
3
Check the oxygen sensors (pre-catalytic and post-catalytic) for proper operation and any wiring issues.
4
Measure the voltage and signal readings from the pre- and post-catalytic oxygen sensors using a multimeter.
5
Inspect the catalytic converter for physical damage or clogs by performing a temperature test or backpressure test.
6
Check for exhaust leaks upstream of the catalytic converter that may affect sensor readings.

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
•Socket set
•Multimeter
•Jack and jack stands
•Safety glasses
•Gloves

Parts Required

•Oxygen sensors (pre-catalytic and post-catalytic)
•Catalytic converter (if damaged)
•Anti-seize compound

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Diagnostic Steps

1
Scan the vehicle’s computer system using an OBD-II scanner to confirm the P0420 code and check for any additional codes.
2
Inspect the exhaust system visually for any signs of damage, leaks, or loose connections.
3
Check the oxygen sensors (pre-catalytic and post-catalytic) for proper operation and any wiring issues.
4
Measure the voltage and signal readings from the pre- and post-catalytic oxygen sensors using a multimeter.
5
Inspect the catalytic converter for physical damage or clogs by performing a temperature test or backpressure test.
6
Check for exhaust leaks upstream of the catalytic converter that may affect sensor readings.

Solution

1. Preparation

Tools Required: OBD-II scanner, socket set, multimeter, jack and jack stands, safety glasses, gloves.
Ensure the vehicle is parked on a level surface and the engine is cool. Disconnect the battery.

2. Oxygen Sensor Replacement (if needed)

Locate the oxygen sensors: The pre-catalytic sensor is located before the catalytic converter, and the post-catalytic sensor is after it.
Disconnect the electrical connectors from both oxygen sensors.
Use a socket wrench to remove the oxygen sensors from their mounting locations.
Install the new oxygen sensors: Apply anti-seize compound to the threads and torque to manufacturer specifications (usually around 30 lb-ft).
Reconnect the electrical connectors.

3. Catalytic Converter Inspection/Replacement

Inspect the catalytic converter for any visible signs of damage or clogging.
If replacement is necessary, use a socket set to remove the flange bolts or clamps securing the catalytic converter to the exhaust system.
Carefully remove the old catalytic converter and replace it with a new unit, ensuring correct orientation.
Reinstall the bolts or clamps and torque to manufacturer specifications (typically around 40 lb-ft).
Reconnect any exhaust hangers that were disconnected during the process.

4. Final Checks

Reconnect the battery terminal.
Start the engine and allow it to reach operating temperature. Check for exhaust leaks around the newly installed components.
Clear the P0420 code using the OBD-II scanner and take the vehicle for a test drive to ensure the code does not return.