Catalytic Converter– A catalytic converter is responsible for scrubbing out as much pollution as possible from the Accord’s exhaust.

If the engine does not exhibit any of the decreased performance associated with a bad catalytic converter, it very well may be the oxygen sensor (or you haven’t noticed the performance loss yet). When the oxygen sensor is bad, it can cause a false reading and trigger the code.

Oxygen Sensor– The P0420 codes is thrown when the oxygen sensors on both sides of the exhaust have very similar readings.

There are many things that can cause the P0420 trouble code in your Accord.

Service Engine Light– Often, this is the only symptom of the Honda Accord P0420 code.

It’s very similar to the symptoms of a bad fuel filter. Whenever the engine is put under a heavy load it’ll feel like it is running out of gas. Typically, they’ll idle ok and drive normal under a light load.

Loss of Power– It is a really strange feeling to drive a vehicle with a catalytic converter that is going out.

Mileage- May or may not suffer depending on how much the catalytic converter is clogged.

Here are the typical symptoms that something is wrong when you have code P0420. For most people the first sign that anything is wrong at all is the service engine soon light coming on.

There aren’t usually any drivability issues associated with P0420. Typically, the code will be triggered by the upstream oxygen sensor (before the converter). The P0420 code in a Honda Accord will often be thrown one of your oxygen sensors are not functioning properly. If your vehicle has the P0420 code, it won’t pass emissions so please be aware of that. The software in your vehicle believes that the catalytic converter is no longer doing its job. When the readings from the upstream and downstream oxygen sensors show similar readings, the vehicle will throw the service engine soon light (P0420). Among the many jobs that oxygen sensors have is they have to measure the emissions levels coming in and out of the converter.

Your Accord has at least two oxygen sensors, one before and after the catalytic converter. The code technically stands for:Ĭatalyst System Efficiency Below Threshold P0420: Catalyst System Efficiency | Below Threshold It doesn’t matter which model you have, this OBDII code has the same meaning for all of them. This code number references a number that is given to you when you plug your Honda Accord into a OBDII scanner. One of the most common trouble codes with all Honda vehicles is the P0420.

In the Accord, OBDII P0420 is often caused by a bad oxygen sensor, but there can be other causes as well. It covers Honda Accord P0420 meaning, symptoms, causes, and possible solutions. This page is meant to help you troubleshoot the Honda Accord P0420 trouble code.

2010 honda accord 3.5 bank 2 convertor