P0422 Fault Code

Main Catalyst Efficiency Below Threshold (Bank 1)

• What does that mean?
• Symptoms
• Causes
• Solutions

The P0422 fault code indicates that the engine control module (ECM) has detected that the catalytic converter efficiency for bank 1 is below the expected threshold. This means the catalytic converter is not efficiently converting harmful exhaust gases into less harmful emissions.

• It usually refers to issues with the catalytic converter itself, the oxygen sensors, or the exhaust system.
• Proper conversion of pollutants is essential for meeting emissions standards and maintaining fuel efficiency.

What are the symptoms of the P0422 code?

Symptoms that may accompany a P0422 code include:

• Check Engine Light illuminated on the dashboard.
• Decreased fuel efficiency as a result of poor emissions control.
• An unusual smell of rotten eggs, which can indicate a failing catalytic converter.
• Poor engine performance, including reduced power and acceleration.

What causes the P0422 code?

Common causes of the P0422 code include:

• A failing catalytic converter that may be clogged or damaged.
• Faulty oxygen sensors which may provide incorrect readings to the ECM.
• Exhaust leaks upstream of the oxygen sensors that can affect their performance.
• Poor fuel quality or unburnt fuel entering the exhaust system.
• Issues with engine timing, which can impact combustion efficiency.

How to fix P0422?

To resolve the P0422 fault code, consider the following steps:

• Start by inspecting the exhaust system for any leaks or damages that may affect sensor readings.
• Test the oxygen sensors to ensure they are functioning properly and replace them if necessary.
• If the sensors are fine, check the catalytic converter for clogs or damage – it may need cleaning or replacement.
• Ensure that the engine is running optimally to prevent further issues, which may involve addressing fuel and air intake problems.