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Jan 20, 2019 - 6 minute read

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Check Catalytic Converter with Scan Tool: How To Guide

ANCEL AD310 Universal OBD II Scanner
(Last Updated On: October 4, 2020)


Scan tools are useful for diagnosing problems with vehicles that are 1996 and newer because they have the necessary sensors installed to generate readings for various engine components.

Catalytic Converter with Scan Tool

Catalytic Converter with Scan Tool

Firstly, you should know if the check engine light illuminates when you start the vehicle. This is the first step in diagnosing the problem. Then, you can use a scan tool to help you figure out why the check engine light has switched on. Even if the issue is nothing to do with the catalytic converter, the OBDII scan tool will still help you figure out the cause of the check engine light.

How To Use A Scan Tool To Check Your Catalytic Converter

Using a scan tool is relatively easy to process, here are the steps:

  • Step 1: Take the connector for the scan tool and plug it into the OBDII port which should found on the left-hand side of the steering wheel.
  • Step 2: Turn on the vehicle and left it run for 10-15 minutes to increase the temperature
  • Step 3: If your scan tool reads back code P0420, then there is a problem with the catalytic converter. See below for a full list of codes.
  • Step 4: Go to live data on your sensor
  • Step 5: Click on the O2 (oxygen sensor) data
  • Step 6: If the O2S12 sensor fluctuates from very high to very low, then there is a problem.

Catalytic converter codes include: P0420, P0421, P0422, P0423, P0424, P0425, P0426, P0427, P0428, P0429, P0430, P0431, P0432, P0433, P0434, P0435, P0436, P0437, P0438, P0439

Best Scan Tools for Catalytic Converters

Don’t own a scan tool? Here are the three best options on the market. 

This is the most affordable option that provides the best value for the price. It is beginner-friendly to use but offers a wide array of advanced features. For example, it diagnoses trouble codes for check engine light/malfunction indicator lamp, performs the I/M monitor readiness test, has an LCD screen, and includes a 2.5 feet long cable that connects to the majority of vehicles that are 1996 or newer.

The Autel Autolink AL519 OBD2 Scanner is a car code reader intended for intermediate level users. It is straightforward to use and can diagnose generic, manufacturer-specific, and pending trouble codes. It is suitable for turning off the check engine light and resetting monitors. Autel is a leader in the scan tool sector, and this is one of their most popular and well-known model of products.  

A leader makes this OBD2 scanner in the scan tool space. It is compatible with most 1996-2013 GM, Ford, Hyundai, Toyota, Nissan, Chrysler, and Honda vehicles. It retails near $300 and is considered an advanced tool. Primarily, it is intended for users that need to read codes for diagnosing vehicles on a regular basis. It is not only for reading diagnostic trouble codes but can graph engine data, record, and playback stored vehicle information, and is equipped with CodeConnect, ABS and airbag display.  

Additional Method: Temperature Gun For Your Cat Converter

This method is to confirm that there is indeed a problem with the catalytic converter. With modern temperature guns, you do not need to do anything other than point the laser beam at the converter. In other words, there is no need to drill a hole into the converter.

Temperature Gun For Your Cat Converter

Temperature Gun For Your Cat Converter

Just measure the temperature of the front and back of the converter. The area in which the air enters the catalytic converter should be warmer than the other end at which the air exits. Therefore, the entrance point should give a higher temperature reading, and the exit point should produce a lower temperature reading. If the texts are the same, then that means that the chemical reactions are not taking place and that the converter is not performing its intended job.

One of the best temperature guns for testing a catalytic converter is the AstroAI Digital Laser Infrared Thermometer. Its distance to spot ratio is 12:1 which makes it easy to use from a far-away distance because getting close to the catalytic converter mounted on your vehicle may be difficult if you don’t own a jack stand. It can measure in both Fahrenheit and Celsius degree temperatures.  The gun itself works by pressing and aiming. Its temperature range is between negative 58 degrees Fahrenheit and positive 1022 degrees Fahrenheit. Regarding its power source, it uses a 9-volt battery. 

Final Words

It is relatively easy to use a OBDII scan tool to figure out and diagnose the problem with your vehicle and the cause behind the malfunction indicator lamp. Use the steps above to check your catalytic converter with a scan tool and DO NOT CAT DELETE!