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There are many issues that could activate the Check Engine Light. If you get the OBD-II code P0422 after a quick scan, this could mean that there is an issue in your vehicle’s emission system. Read on to learn more about code P0422, the symptoms you should look out for, and the possible triggers of the code.

What Does the P0422 Code Mean?

Diagnostic trouble code (DTC) P0422 stands for “Catalyst 2 Efficiency Below Threshold (Bank 1).” It indicates that the emissions efficiency of Bank 1 catalytic converters are below the minimum allowable limit. This threshold is monitored by the catalyst monitor oxygen sensor, which is located near the catalytic converter’s outlet.

The purpose of your car’s catalytic converter is to oxygenate the exhaust gasses and improve tailpipe emissions. It is monitored by the catalyst monitor oxygen sensor.

catalytic converter 2 1
The purpose of your car’s catalytic converter is to oxygenate the exhaust gases and improve tailpipe emissions.

The engine control module (ECM) tracks the switching frequency of the heated oxygen sensors 1 and 2 (front and rear sensors). A functional three way catalyst converter typically indicates a low switching frequency of heated oxygen sensor 2. The frequency increases as the converter deteriorates.

The P0422 code is logged when the frequency ratio of both heated oxygen sensors 1 and 2 reaches the threshold.

You can get more helpful information in our technical discussion about how cat converters work and catalytic converter efficiency.

What are the Common Causes of the P0422 Code?

Here are some common triggers of the error code P0422:

  • Defective catalytic converter
  • Defective oxygen sensor
  • Exhaust leak
  • Damaged catalytic converter due to engine misfires
  • Damaged catalytic converter due to a leaking head gasket
  • Internal engine damage leading to high oil consumption

What are the Possible Symptoms of the P0422 Code?

Depending on the severity, other related diagnostic trouble codes may also be stored. Expect an illuminated check engine light once the P0422 code is logged. In most cases, the engine code exhibits no other noticeable symptoms.

How to Diagnose the P0422 Code

Because the error code P0422 is generic, it is supported by various makes and models. This can make its diagnosis and repair difficult for the average DIYer. To help you understand and troubleshoot this error code better, check out the video below:

How to Fix the P0422 Code

Like most OBD-II codes, the P0422 code shares similar causes and symptoms with several other engine codes. However, resolving this error code takes more than just a generic solution. It’s better to leave the repairs to the experts if you aren’t confident in your automotive repair skills.

The code could be triggered by anything from a defective catalytic converter to a faulty oxygen sensor, so you must do your research thoroughly. Keep in mind that all vehicles are different. It’s important to always consult your owner’s manual and the factory repair information before DIY-ing any repairs.

Consult online auto repair sources for guidance. For instance, an ALLDATA subscription provides detailed factory repair information that you can use to accurately resolve issues in your car. This should help you resolve this error code and other fixes you may need to carry out in the future.

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Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic.

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