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Knowing This 1 Tip Can Save Your Toyota Prius From Setting A P0420 Trouble Code

Anyone can google what a P0420 code means. Determining the root cause of the issue is what needs to happen rather than putting a band-aid on the problem. Here is what you need to know about keeping your Prius under control.

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Any trouble code on a Toyota Prius could mean big bucks. With several common issues that the Toyota Prius faces, another problem to work through can seem awful. What is worse is having to do a repair multiple times.

I want to cover what a P0420 code is, and how it can be activated from a commonly found issue with our Prius cars. This way if you get a code on your Prius, you will know just what to do. Here is what a P0420 code is and what you need to know to fix the root cause of it.

What a P0420 Code Means On A Toyota Prius
The actual definition of a P0420 code is Catalyst System Efficiency Below Threshold (Bank 1). This may seem technical, but it really is not.

A catalyst or catalytic converter is a device that uses a catalyst to convert three harmful compounds in car exhaust into harmless compounds. The converters on Prius are rather robust and have to be in order to be environmentally friendly. That means if they are not functioning as designed, Prius is polluting the air more than we want it to be.

Why Does Prius Set The P0420
Prius has a known issue of oil consumption that you can read about here. This process is part of the reason that catalytic converters fail. The oil residue coats the precious metals inside the converter and reduces its ability to convert harmful gasses into less harmful gasses.

Toyota Prius Catalytic Converter Failure Rate

The way that Toyota Prius ensures that it is staying economically friendly is to monitor the catalyst and set a trouble code should it fail. This is where the powertrain code P0420 comes in to play. The ECU monitors the converter through the use of oxygen sensors. The sensors check the converter to ensure it is doing the job it is designed to. That means then if the converter fails it will set the trouble code.

Fixing The Root Cause Of The Problem
The real reason that a catalytic converter can fail on a Toyota Prius is due to that oil consumption issue as stated before. So, now that we know that, how to do keep from replacing catalytic converters all the time. The answer is simple, fix the root problem.

Toyota Prius Engine Oil Bottles Oil Consumption

If the root cause is oil consumption, then fixing or reducing that issue will prolong the life of your catalytic converter. It really is that simple.

If you have experienced a P0420 trouble code with your Toyota Prius, and are experiencing oil consumption, take care of the root issue first. Check out my other articles on oil consumption to see how you can fix this problem in your own driveway.

Watch 3 reasons you should consider selling your Toyota Prius and click to subscribe to Torque News Youtube channel for daily automotive news and analysis.

Thank you for reading, please check out my other story, Do Toyota Prius Owners Obsess Too Much Over Fuel Economy?

Peter Neilson is an automotive consultant specializing in electric cars and hybrid battery technologies. He holds a Bachelor of Science in Automotive Service Technology from Weber State University. Peter is also an Instructor of Automotive Technology at Columbia Basin College. Peter can be reached on Linkedin and you can tweet him at The_hybrid_guy on Twitter. Find his page on Facebook at Certified Auto Consulting

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Joachim Bordt (not verified)    October 5, 2021 - 7:06AM

I have seen a P0420 code for years now. Erasing the code, it will show up eventually again. The car Runs fine. NO oil consumption with CASTROL 0-W30.
P1 202, 580t km, mica-green.