P0422 OBD-II: Main Catalyst Efficiency Below Threshold

P0422 Severity

Urgent

Should you fix P0422 yourself?

Identifying an OBD code is just the start of a complete diagnostic routine. Most trouble codes are caused by a sensor reporting a value that is out of range. Just replacing a sensor may not fix underlying issues. Be sure to understand the code, the part or system in your car that the code refers to, and the risks of delaying professional repair.

Proper diagnosis will save you time and money on unnecessary repairs.

Urgent codes indicate immediate action is necessary. These are urgent and significant malfunctions that can cause severe damage to the vehicle or harm the driver and passengers.

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What causes OBD-II fault code P0422?

The Catalytic Converter takes the exhaust gases left over by the combustion process and converts those gases to harmless emissions. The engine control module (PCM) compares the front and rear oxygen sensors to each other to determine catalytic converter efficiency. If the input from the rear oxygen sensor starts to match the front oxygen sensor, the PCM will set code P0422.Catalytic converters are covered under federally mandated 8yr/80,000 mile warranty by the vehicle's manufacturer. Catalytic converters usually fail as a result of something else (engine misfire, internal oil leak, or internal coolant leak) not being repaired. The original cause of the failure is usually not covered under warranty.

OBD II Fault Code

OBD II P0422

Fault Code Definition
Code P0422 indicates that the Bank 1 Main Catalytic Converter's emissions efficiency has fallen below the minimum allowable limit. This threshold is tracked by a Catalyst Monitoring Oxygen Sensor located on or near the outlet of the Catalytic Converter.

P0422 Symptoms

Check Engine Light will illuminate
In many cases, no abnormal symptoms may be noticed

Common Problems That Trigger the P0422 Code

Defective Catalytic Converter
Engine misfires have damaged the Catalytic Converter
Internal engine damage resulting in high oil consumption and/or a leaking Head Gasket has damaged the Catalytic Converter

Common Misdiagnoses

Oxygen Sensor(s) are replaced when the real problem is a damaged Catalyst
Catalyst is replaced when the real problem is internal engine damage, which is producing elevated emissions levels
Catalyst is replaced when a misfiring engine is the real problem

OBD Code Resources

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OBD II Fault Code

OBD II P0422

P0422 Symptoms

Check Engine Light will illuminate
In many cases, no abnormal symptoms may be noticed

Common Problems That Trigger the P0422 Code

Defective Catalytic Converter
Engine misfires have damaged the Catalytic Converter
Internal engine damage resulting in high oil consumption and/or a leaking Head Gasket has damaged the Catalytic Converter

Common Misdiagnoses

Oxygen Sensor(s) are replaced when the real problem is a damaged Catalyst
Catalyst is replaced when the real problem is internal engine damage, which is producing elevated emissions levels
Catalyst is replaced when a misfiring engine is the real problem

P0422 OBD-II: Main Catalyst Efficiency Below Threshold

Should you fix P0422 yourself?

What causes OBD-II fault code P0422?

Need a P0422 diagnosis? Trust our experts.

OBD II Fault Code

P0422 Symptoms

Common Problems That Trigger the P0422 Code

Common Misdiagnoses

OBD Code Resources

Need a P0422 diagnosis? Trust our experts.

Ask our experts about P0422.

Other OBD-II Codes

OBD II Fault Code

P0422 Symptoms

Common Problems That Trigger the P0422 Code

Common Misdiagnoses