1. Year
2. Make
3. Model
4. Trim
5. Fuel Type

Great news! FIXD is compatible with your vehicle.


Unfortunately, FIXD is not guaranteed to be compatible with your vehicle.

Fix P0420 yourself!

Ford Explorer P0420 – Meaning, Causes, Symptoms, & Fixes


What Does Ford Explorer Code P0420 Mean?

  • Ford Explorer P0420 definition: Catalyst system efficiency below threshold (Bank 1)
  • Issue Severity: MODERATE – Extended driving with this code can cause internal engine damage.
  • Repair Urgency: Get this code fixed as soon as possible to avoid further damage to your emission system and possible engine damage.
  • Diagnosis: The most common cause of Ford Explorer P0420 is a bad catalytic converter, but it can be caused by anything from a faulty oxygen sensor to a rich or lean running condition, or misfires. There are many variables that could cause this code. You can take your car into a shop, or click here to save money by fixing P0420 yourself with FIXD!

The function of the catalytic converter is to break down harmful pollutants that are created by your Ford Explorer during the combustion cycle and convert them into less harmful gases. Code P0420 indicates that the catalytic converter is not functioning efficiently, therefore increasing the output of harmful pollutants by the vehicle.

Most Likely Repair And Cost For Ford Explorer P0420 By Year

The chart below shows the most likely repair and cost range for Explorers for all of the years that FIXD has data on.

Year Most Likely Repair Cost Range
2016 Catalytic Converter(s) w/P0430 $1538 – $2041
2015 Catalytic Converter(s) $1538 – $2041
2014 Catalytic Converter(s) $1538 – $2041
2013 Catalytic Converter(s) $1538 – $2041
2012 Catalytic Converter(s) $1538 – $2041
2011 Catalytic Converter(s) $1538 – $2041
2010 converter has failed (check for physical damage and discoloration) $0 – $0
2009 Catalytic Converter(s) w/P0430 $1538 – $2041
2008 Catalytic Converter(s) $1538 – $2041
2007 Catalytic Converter(s) $1538 – $2041
2006 Catalytic Converter(s) $1538 – $2041
2005 Catalytic Converter(s) w/P0430 $1538 – $2041
2004 Catalytic Converter(s) $1538 – $2041
2003 Catalytic Converter(s) $1538 – $2041
2002 Catalytic Converter(s) $1538 – $2041
2001 Oxygen (O2) Sensor Connector w/P0133 $50 – $150
2000 Catalytic Converter(s) $1538 – $2041
1999 Catalytic Converter(s) $1538 – $2041
1998 Catalytic Converter(s) $1538 – $2041
1997 Catalytic Converter(s) $1538 – $2041
1996 Catalytic Converter(s) $1538 – $2041

Ford Explorer P0420 Causes

The most common reason for check engine code P0420 is catalytic converter failure, but there are other potential causes for this code. It’s important to look for other codes that could indicate the root cause of converter failure, such as misfires or an incorrect air-fuel ratio. Our P0420 guide can walk you through how to save money and diagnose this yourself.

  • Worn or internally failing catalytic converter (Most Common)
  • Faulty oxygen sensor
  • Faulty air-fuel sensor
  • A leak in the exhaust system
  • Misfire (the root cause of converter failure)
  • Rich or Lean air-fuel ratio (the root cause of converter failure)
  • Leaded Gasoline (the root cause of converter failure)
  • P0420 is one of the top 5 trouble codes for the Ford Explorer.

Ford Explorer P0420 Symptoms

  • Check Engine Light is on
  • Lack of power from the engine
  • Decreased fuel economy
  • Rotten egg or a sulfur smell

How Do I Fix Ford Explorer Code P0420?

The first step is to get it diagnosed to figure out what is causing the catalytic converter fault.

If you’re having catalytic converter issues and you’re not comfortable diagnosing this issue at home, we recommend finding a RepairPal certified shop nearby to pinpoint the problem and give an accurate estimate for repairs.

These shops can not only help you figure out what’s going wrong before you waste time and money on the wrong parts, but they also offer a minimum 12-month, 12,000-mile warranty and stand behind all their estimates with guaranteed fair pricing.

> Find a RepairPal Certified Shop Near You

DIY Steps to Diagnose Ford Explorer Code P0420

If you’d like to try to fix code P0420 at home without throwing money at parts, you’ll want to follow the steps below for proper diagnosis. Keep in mind this is an advanced-level diagnosis and repair and not recommended for beginners. Diagnosis can be a time and labor-intensive process for inexperienced DIYers. If you want a step by step guide on how to diagnose and fix this problem, check out our P0420 guide.

DIY difficulty level: Advanced

This repair requires mechanical knowledge and is not recommended for beginners.

Tools/parts needed (our top picks from Amazon):


Use FIXD to scan your Ford Explorer to verify P0420 is the only code present. If other codes are present, they must be addressed first.


Pay close attention to the exhaust manifold, gaskets, and exhaust pipes pre-catalytic converter. If any leaks are found, repair the leak, clear the code, and complete several drive cycles to verify that was the fix.


With the vehicle running and at normal operating temperature, use the FIXD live data feature or a digital multimeter to check the voltage reading of the downstream O2 sensor. The downstream O2 sensor produces a relatively steady voltage reading of approximately 0.45V if the catalytic converter is functioning properly. If the voltage of the downstream O2 sensor is constantly jumping between 0.1V and 0.9V, the catalyst is worn and the catalytic converter needs to be replaced.

Common P0420 Diagnosis Mistakes

Oftentimes, this code is thought to be a faulty O2 sensor or A/F Sensor. While this is a possibility, the most common problem is a faulty catalytic converter. Do not overlook other codes that are paired along with P0420. Codes like P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, and P0308 are misfire codes, and these codes require misfire diagnosis. If the catalytic converter is replaced without repairing the misfire, the new catalytic converter will go bad again. Also, make sure you don’t have codes P0174, P0171, P0172, or P0175 which can mean the engine is running rich or lean, which can burn out your catalytic converter. If these codes or any other codes are present, they should be addressed first.

Still Need Help Fixing Ford Explorer Code P0420?

If you’ve followed the steps above and are still experiencing Ford Explorer check engine code P0420, please contact the FIXD Mechanic Hotline if you’re a FIXD Premium subscriber or find a RepairPal certified shop near you for proper diagnosis and fair pricing.

Fixed It But The Check Engine Light Is Still On?

Check engine light sometimes need to be reset manually, check out our article:

How to Reset Your Check Engine Light | 4 Ways To Clear It (With or Without a Scanner)

FIXD Research Team

At FIXD, our mission is to make car ownership as simple, easy, and affordable as possible. Our research team utilizes the latest automotive data and insights to create tools and resources that help drivers get peace of mind and save money over the life of their car.

Find a Certified Shop

We've partnered with RepairPal to recommend trustworthy shops in your area. Enter your details to see certified shops near you that offer upfront estimates, guaranteed fair pricing, and a minimum 12-month, 12,000-mile warranty.

We’re here to help you simplify car care and save, so this post may contain affiliate links to help you do just that. If you click on a link and take action, we may earn a commission. However, the analysis and opinions expressed are our own.


About the Author

FIXD Research Team

FIXD Research Team

At FIXD, our mission is to make car ownership as simple, easy, and affordable as possible. Our research team utilizes the latest automotive data and insights to create tools and resources that help drivers get peace of mind and save money over the life of their car.

You might also like

Explore Car Resources

car insurance icons

Car Insurance

Find the best insurance deals for your car

Car Buying

Everything you need to know about buying a vehicle

FIXD Team logo

Car Care

Car repair costs, how-to guides, and more

car buying icons

Vehicle Search

Search any make/model for reviews, parts and more