How To Diagnose And Fix P0420 Yourself

So you’ve discovered you’ve got a P0420 code. That could mean anything from a faulty oxygen sensor to a bad catalytic converter. We do NOT recommend continuing to drive with this code, unless you like the idea of replacing your engine.

Find the cause of your P0420:

Are there any leaks in your exhaust system?
Are your O2 sensors working?
Do you need to replace your O2 sensor wires?
Is your catalytic converter broken?
Is another code causing the P0420?

If you can pinpoint the cause of your P0420, you will know exactly what you need to fix without wasting money on replacement parts you don’t need.

Now for some GOOD news

Everything you need to diagnose and fix P0420 with confidence is at your fingertips inside our easy-to-follow 15-page guide! Whether you’re mechanically inclined or know nothing about cars, this guide was created by one of our car experts, Jeffrey Ross (a former ASE Certified mechanic and lifelong gearhead), to help you get the job done – without all the headaches and guesswork.

FIX P0420 YOURSELF WITH FIXD'S P0420 DIY REPAIR PACK

Your risk-free P0420 DIY Repair Pack gives you everything you need to diagnose and understand how to fix your P0420 for $4.99 ($150 value). If it doesn’t save you money, return it no questions asked. Your guide will be emailed to you after you complete checkout

What's included?

You’ll get our 15 page step by step guide to fixing P0420 with images, diagrams, and videos. You’ll also get one FIXD Sensor (FREE Shipping) and a 14-day risk-free trial of FIXD Premium, which includes unlimited access to our unbiased mechanic hotline and all of these other great features you’ll love:

Access our data network to see the most likely fix for your check engine light code and how much it should cost so you don’t get ripped off.

Whether you want someone to walk you through DIY repairs, help you schedule service, or just explain what’s going on with your car in simple terms, our FIXD Mechanics have you covered. Call Monday-Friday, 8am to 8pm EST, for trusted advice you can count on.

Buying used? Use your FIXD Sensor + Premium to scan any car for hidden issues and view the complete history of any vehicle you’re interested in, including its fair market value, previous accidents, mileage, & more.

With Issue Forecast, you can find out what issues your vehicle is most likely to encounter in the future so that you can plan ahead and take steps to avoid them with proper maintenance.

FIXD Premium includes our Emissions Precheck feature so that you can test emissions at home and make sure you’ll pass before wasting time and money at a testing facility.

As part of your risk-free, no-cost 14-day trial, you’ll also receive a FIXD Sensor. This car scan tool connects to your vehicle’s OBD2 port to read and decode check engine lights. The following features are included free with your FIXD Sensor:

- Translate 7000+ check engine codes into simple terms on your phone
- Get accurate cost estimates for your vehicle for any common repairs
- Get maintenance alerts that tell you when it’s time for an oil change, tire rotation, & more
- Find trustworthy, RepairPal Certified mechanics near you with the Shop Finder Tool
- See how severe your issue is so you know if it’s safe to drive
- Access our library of how-to content so you can DIY and save $$$
- Use the Manual Diagnostic Tool to find out what’s causing those funny noises under the hood
- And more for FREE with your FIXD Sensor and 14-day trial

How does FIXD work?

Plug in the sensor

FIXD plugs into your car’s OBD2 port (every car made since 1996 has one), usually located under the steering wheel.

Start your engine

Download the FIXD app and start your engine. The FIXD Sensor easily connects to your smartphone via Bluetooth.

Tap to scan!

Hit the “scan” button on your phone to instantly decode your check engine light and access all Premium features!

FIXD is compatible with all gas-powered vehicles manufactured in 1996 or newer, and all diesel engines 2008 or newer.

Our no-holds-barred, 100% risk-free guarantee

You might think we’re crazy to give away the FIXD Sensor and our Premium app subscription FREE for 14 days with the P0420 Guide, and… maybe we are. But that’s how confident we are that you’re going to love your new “pocket mechanic.” And if you do, that’s great! You get to keep the sensor for free and you’ll be charged $69.99, or only $5.83/month, for a full YEAR of Premium benefits ($120 value).

We know you’ll love this, but we get it, saving money and simplifying car care simply isn’t for everyone. So if you take FIXD Premium for a risk-free spin today and don’t end up loving it, no hard feelings – and no charge! Simply send the FIXD Sensor back after your 14-day trial and you won’t be charged a penny. There’s literally nothing to lose, so let’s get started!

See why millions of drivers love FIXD

The main use is the cost estimates for everything. It’s powerful to be able to hold that up to the mechanic and be like ‘wait a second, that estimate is way over.'

My family has saved thousands of dollars in labor alone. Thank you! Over 6 different vehicles have been fixed using FIXD Premium.

Love FIXD Premium. Went to a mechanic and he told me I needed much more done to my Hyundai and I told him to fix only what the app said to repair. He then asked how I know, I showed him the FIXD recommended repair and cost. Never went back.

This has been a big money saver for me. I was having car problems and I took it to the shop. $500 to fix the car. I decided to buy this before doing the repairs and glad I did. The problem was just a mass air flow sensor. Part was only $90 and I went on YouTube and fixed it in 15 minutes with a screw driver.

If you own a vehicle you absolutely have to get one, I put in the info and it told me exactly what the problem was and rated the seriousness of it, and provided locations where I could get it fixed without getting overcharged.

Easily top 3 if not top product I have ever purchased on Amazon. Easy to set up, install, and use. The premium service is excellent with a 24/7 mechanic helpline (who went above and beyond). I had a check engine light come in with a throttle control motor specifies as the issue. In total I spent $50 for the Device, $9 for a month of premium, and $20 on a relay. Problem solved (after talking it through with the call in mechanic). I spend $79 total, or could pay $120 for a diagnostic, and still not resolve my issue. 100% would purchase again and recommend.

I called the mechanic hotline and believe you me, my money... was well spent. I spoke to John and he was a gentleman. Didn't talk down to me... answered my questions and told me to never hesitate to call for any reason about the car. Thank you so much for the ability to call a mechanic when I need help. I appreciate it and believe you me I will tell everyone what a class A company FIXD is.

Frequently Asked Questions

Why should I take you up on this offer?

Honestly? It’s the best deal we’ve ever run in our 8-year history and we’re not sure when we’ll take it down. With your P0420 Guide, you get to take the FIXD Sensor AND FIXD Premium for a risk-free test drive for the next 14 days for $0 out of pocket. You don’t even have to pay shipping on the sensor we’re going to send you as part of your free trial! There’s literally nothing to lose, so what are you waiting for? Let us help you simplify car care.

What's included in my FREE 14-day trial?

Your 100% risk-free trial costs you nothing and includes 1 FIXD Sensor and a 14-day trial to FIXD Premium. You’ll get to take all the standard features of our free app for a test drive, plus the following Premium features!

FIXD Mechanic Hotline: Call anytime for second opinions, at-home repairs, and more
Confirmed Fix & Cost: See the most likely fix for your check engine light and how much it should cost
Issue Forecast: Predict future problems and avoid costly repairs down the road
Vehicle History Report: Get the complete history of any vehicle before you buy used. See accident history, scan for check engine lights, see fair market value, and more
Emissions PreCheck: Make sure you’ll pass emissions testing the first time with this easy at-home test exclusive to FIXD Premium

Click here to get your P042 Guide and start your free trial with FREE FIXD Sensor >>

What happens after my free trial ends?

After your risk-free 14-day trial, you can keep the sensor (normally $59) at no charge and keep on crushing car care with easy check engine diagnostics, access to our FIXD Mechanics, repair cost estimates, and more. We’ll bill you for the yearly subscription at $69.99 so you get uninterrupted access to FIXD + FIXD Premium.

What if I don't like FIXD?

Let’s not get ahead of ourselves, but we’re confident you’re going to love your new FIXD Sensor and Premium features. That’s why we’re giving away free test drives! That being said, we understand if it’s not right for you. So, if after the 14 days you don’t wish to continue, all you have to do is mail back your FIXD Sensor to headquarters here in Atlanta and you won’t be charged a dime.