Chrysler Town and Country P0420: Catalyst System Efficiency → Below Threshold → Bank 1

This page was created to assist you in troubleshooting the problem. Chrysler Town and Country Trouble Code P0420. This article covers Chrysler Town and Country OBDII P0420 symptoms, causes and potential solutions. The most common cause of OBDII P0420 in Chrysler Town and Country is a bad oxygen sensor. However, there are other possible causes. It can be costly to spend your time replacing the O2 sensor.

Chrysler Town and Country P0420 Diagnosis


The most common trouble code is P0420. The code refers to a number you receive when your Chrysler Town and Country is plugged into an OBDII scanner. It doesn’t matter which model you have, this OBDII code has the same meaning for all of them (1996+)


Índice de Contenido
  1. Chrysler Town and Country OBDII Code Definition
  2. Chrysler Town and Country P0420 code Symptoms
  3. The Top Reasons for P0420 in Chrysler Town and Country
  4. Possible Solutions: Chrysler Town and Country, P0420 Code

Chrysler Town and Country OBDII Code Definition

Town and Country P0420 Code Symptoms

P0420 It is an OBDII trouble code. This code is technically:

Low Catalyst System Efficiency

At least two oxygen sensors are installed in your Town or Country, one just before and one after the catalytic convertor. They are responsible for measuring the emission levels from the converter, one of many important jobs.

The vehicle will soon turn on the service engine if the oxygen sensor readings upstream and downstream are similar (P0420).

These readings shouldn’t match, since the catalytic converter is supposed to be scrubbing the exhaust. The software of your Town and Country will determine if the numbers match.


Chrysler Town and Country P0420 code Symptoms

P0420 Chrysler Town and Country

Your oxygen sensors may not be working correctly and the code P0420 will appear in your Chrysler Town and Country. The code is usually triggered by an oxygen sensor upstream (before the converter).

There aren’t usually any drivability issues associated with P0420. The first indication that something is amiss is usually the soon-light coming on in the service engine.

These are some of the symptoms you should look out for if your code is P0420.

  • Fuel Efficiency- It is possible for your catalytic converter to become clogged.
  • The loss of power– It is a really strange feeling to drive a vehicle with a catalytic converter that is going out. Typically, they’ll idle ok and drive normal under a light load. Whenever the engine is put under a heavy load it’ll feel like it is running out of gas. It’s very similar to the symptoms of a bad fuel filter.
  • Service Engine Light– Often, this is the only symptom of the Chrysler Town and Country code P0420.

Similar: P0442 Chrysler Town and Country


The Top Reasons for P0420 in Chrysler Town and Country

Many things can lead to the P0420 code. These are some of the more common.

  • Oxygen Sensor– The P0420 codes is thrown when the oxygen sensors on both sides of the exhaust have very similar readings. An oxygen sensor that is defective can give false readings and cause the code to be triggered. 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 (if you haven’t noticed the performance loss yet).
  • Catalytic Converter– A catalytic converter is responsible for scrubbing out as much pollution as possible from the Town and Country’s exhaust. These can become blocked over time. Even though modern catalytic convertors should be able to last many years, it is possible that it has become blocked.
  • The O2 Sensor Wiring– Over time, the oxygen sensor wiring can go bad. Because it's right beside the exhaust, this wiring is extremely volatile. Because it is far away from the ECM, the downstream oxygen sensor wiring can also be volatile. (More distance = greater chance of failure).
  • Timing for Town and Country– If your Town and Country is misfiring or the exhaust timing is off, this can affect the gasses that are actually going to the O2 sensors enough to cause the P0420 code to register.
  • Exhaust Leak– If there’s a noticeable exhaust leak coming from the vehicle it can change what the O2 sensors register enough to throw the P0420 code.
  • Sensor to measure engine temperature– If the computer doesn’t know what the engine temp is it’ll keep the fuel mixture rich. The O2 sensors will not see the mixture richly and could cause it to throw its sensor.


Possible Solutions: Chrysler Town and Country, P0420 Code

P0420 is often caused by the oxygen sensor. Specifically it’ll usually be the O2 sensor(s) on the upstream side of the catalytic converter.

But, don’t be surprised if it’s not. You should check your exhaust first for any leaks. An exhaust leak should sound easily beneath the car.

Unless you have an exhaust leak, you’ll probably need to test the O2 sensors and/or catalytic converters. Below are some good guidelines to assist you in this task.

You will be able to solve the problem with Chrysler Town and Country P0420. You can comment on the article or send a message if there are inaccuracies or any suggestions. Many thanks.

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