AutoCodes – Ford – P0420 2010 Ford Fusion

P0420 2010 Ford Fusion Code - Catalyst System Efficiency Below Threshold Bank 1

Quick Answer

The Engine Control Module (ECM) monitors the switching frequency ratio of heated oxygen sensors 1 (front O2 sensor) and heated oxygen sensors 2 (rear O2 sensor). Common causes include Faulty Three-way Catalyst Converter Bank 1, Exhaust Tube, Intake Air Leaks. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means: P0420 2010 Ford Fusion indicates Catalyst System Efficiency Below Threshold Bank 1.
Common causes: Common causes include Faulty Three-way Catalyst Converter Bank 1, Exhaust Tube, Intake Air Leaks.
Severity: Moderate - service should be scheduled soon.
Can I drive?: The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

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Code Popularity 17,047

How popular is this code, among other codes? Low

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 20, 2020

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0420 2010 Ford Fusion Description

The Engine Control Module (ECM) monitors the switching frequency ratio of heated oxygen sensors 1 (front O2 sensor) and heated oxygen sensors 2 (rear O2 sensor).
A three way catalyst converter (Manifold) with high oxygen storage capacity will indicate a low switching frequency of heated oxygen sensor 2. As oxygen storage capacity decreases, the heated oxygen sensor 2 switching frequency will increase.
When the frequency ratio of heated oxygen sensors 1 and 2 approaches a specified limit value, the three way catalyst malfunction is diagnosed.

OBDII Code P0420 2010 Ford Fusion - Catalyst System Efficiency Below Threshold Bank 1 - AutoCodes.com — P0420 2010 Ford Fusion Code - Catalyst System Efficiency Below Threshold Bank 1

What does this mean?

What are the Possible Causes of the DTC P0420 2010 Ford Fusion?

Faulty Three-way Catalyst Converter Bank 1
Exhaust Tube
Intake Air Leaks
Faulty Oxygen (O2) Sensor
Faulty Fuel injector(s)
Leaking Fuel Injector (s)
Faulty Spark plugs
Improper Ignition Timing
Faulty Engine Control Module (ECM)
Dirty Air Filter

How to Fix the DTC P0420 2010 Ford Fusion?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

As the code description implies the P0420 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0420 code is combined with other codes, try fixing the other codes first.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0420 2010 Ford Fusion code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0420 2010 Ford Fusion Code

1. What are the common symptoms of a P0420 code on a 2010 Ford Fusion?

The common symptoms of a P0420 code on a 2010 Ford Fusion include decreased fuel efficiency, rough idling, and an illuminated check engine light.

2. What does the P0420 code indicate on a 2010 Ford Fusion?

The P0420 code on a 2010 Ford Fusion indicates that the catalytic converter's efficiency in Bank 1 is below the threshold set by the vehicle's computer.

3. What are the possible causes of a P0420 code on a 2010 Ford Fusion?

Possible causes of a P0420 code on a 2010 Ford Fusion include a faulty catalytic converter, oxygen sensor issues, exhaust leaks, or engine misfires.

4. Can a P0420 code on a 2010 Ford Fusion cause any serious damage if left unrepaired?

If left unrepaired, a P0420 code on a 2010 Ford Fusion can lead to decreased engine performance and potentially cause damage to other components over time.

5. How can I diagnose a P0420 code on my 2010 Ford Fusion?

Diagnosing a P0420 code on a 2010 Ford Fusion typically involves performing a thorough inspection of the catalytic converter, oxygen sensors, and exhaust system using a scan tool and other diagnostic equipment.

6. Is it safe to continue driving my 2010 Ford Fusion with a P0420 code?

It is generally safe to drive your 2010 Ford Fusion with a P0420 code, but it is recommended to address the issue promptly to prevent further damage and ensure optimal vehicle performance.

7. Can I reset the check engine light after fixing a P0420 code on my 2010 Ford Fusion?

Yes, you can reset the check engine light using an OBDII scanner after fixing the underlying issue causing the P0420 code on your 2010 Ford Fusion.

8. How much does it typically cost to repair a P0420 code on a 2010 Ford Fusion?

The cost of repairing a P0420 code on a 2010 Ford Fusion can vary depending on the specific cause, but it may range from a few hundred to over a thousand dollars, including parts and labor.

9. Are there any DIY repair tips for addressing a P0420 code on a 2010 Ford Fusion?

While some basic maintenance tasks like checking for exhaust leaks or replacing oxygen sensors can be done by DIY enthusiasts, diagnosing and repairing the root cause of a P0420 code often requires professional expertise.

10. How often does a P0420 code reappear after repair on a 2010 Ford Fusion?

If the underlying issue causing the P0420 code is properly addressed, the code should not reappear on a 2010 Ford Fusion. Regular maintenance and monitoring of the catalytic converter and related components can help prevent future occurrences.