What is the P0420 Toyota Tundra Code?

The P0420 Toyota Tundra Code is an OBD II error that typically indicates a problem with your Toyota Tundra’s catalytic converter. The catalytic converter helps filter pollutants out of the exhaust stream, so its malfunction could lead to other serious health issues.

The catalytic converter is made up of precious metals like platinum, palladium and rhodium; making it a prime target for thieves.


A P0420 Toyota Tundra code is set when one of the oxygen sensors that monitor exhaust gasses exiting your engine sends a reading to the Power Control Module (PCM) that doesn’t match what it should be. The PCM then stores this code so it can be retrieved using a diagnostic tool.

What is the P0420 Toyota Tundra Code?
What is the P0420 Toyota Tundra Code?

The first oxygen sensor measures the amount of oxygen present in exhaust gases before they enter a catalytic converter, and sends these readings to the Power Control Module (PCM). The PCM uses these numbers to adjust your engine’s air-fuel mixture accordingly.

Uncorrectly measured oxygen levels can cause your car’s air-fuel ratio to be too rich, potentially damaging the catalytic converter. Before taking your truck in for repairs, ensure the O2 sensors are functioning correctly.

Your Toyota Tundra’s catalytic converter is an integral part of its exhaust system that transforms hazardous pollutants into less damaging byproducts. If damaged, it can significantly impact performance and emissions levels.


P0420 Toyota Tundra Code is the most frequent OBDII code that signals an issue with your catalytic converter. This component works to filter harmful chemicals and gases from your Tundra’s exhaust.

However, your Toyota Tundra’s converter may malfunction due to several reasons. A malfunctioning oxygen sensor, an engine misfire or an air/fuel mixture that is either too rich or lean can all lead to a P0420 Toyota Tundra Code appearing on its dashboard.

A clogged or worn catalytic converter is the most likely cause of a P0420 Toyota Tundra Code, though it could also be caused by a leak in your Tundra’s exhaust system. If you’re uncertain whether a leak exists, use an infrared thermometer to measure the temperature of the catalyst.

When it comes to taking your Tundra for repairs, the diagnosis time and labor rates vary by shop and location. On average, repair shops will charge between $75-150 an hour for diagnosing an issue with your vehicle.


P0420 is a diagnostic code your Toyota Tundra’s engine control module (ECM) may generate when it believes your three-way catalytic converter isn’t performing optimally. Generally, this indicates that you should replace the catalytic converter.

When your engine’s ECM detects that the catalytic converter isn’t performing as expected, it will illuminate the check engine light to alert you. This government-mandated component filters out harmful exhaust gases and pollutants from your Toyota Tundra’s engine.

If you have a diagnostic tool that can read OBD codes, the most accurate way to diagnose the problem is by connecting it to your Tundra’s OBDII port. From there, search for any error codes related to the catalytic converter.

The P0420 code indicates that the car’s Electronic Control Module (ECM) has detected a decrease in efficiency of Bank 1 of its catalytic converter. Bank 1 is located on the driver’s side of the engine, including cylinder number one.

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What is the P0420 Toyota Tundra Code?


Code P0420, otherwise known as “Catalyst System Efficiency Below Threshold (Bank 1),” is an OBD-II diagnostic code that indicates an issue with one of your vehicle’s catalytic converters. This could be caused by various issues such as misfiring of the engine or malfunctioning oxygen sensor.

Code P0420 is typically due to a malfunctioning catalytic converter. While replacing oxygen sensors may provide temporary relief, in most cases a replacement of the catalytic converter is necessary.

If your car’s catalytic converter requires repair, take it to a service center for accurate diagnosis and repairs. These shops usually provide at least a 12-month warranty as well as guaranteed fair pricing on their estimates.

While a P0420 code may seem minor, it’s still essential to diagnose and address the issue promptly in order to avoid further harm. Furthermore, driving with an inefficient catalytic converter could result in more significant issues such as drivability issues and potential safety hazards.

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