P0422 – OBD-II DTC

OBD-II DTC P0422 – Warm Up Catalyst Efficiency Below Threshold (Bank 1)

DTC P0422 meaning

DTC P0422 indicates that the warm-up catalyst efficiency for Bank 1 is below the expected threshold. The warm-up catalyst is designed to reduce emissions during the initial phase of engine operation when the engine is still warming up. This code suggests that the catalyst is not functioning effectively, which can lead to increased emissions and potential failure to meet regulatory standards.

DTC P0422 symptoms

Common symptoms associated with DTC P0422 may include:

• Check Engine Light (CEL) illuminated
• Decreased fuel efficiency
• Rough engine performance
• Increased emissions
• Failed emissions test

DTC P0422 causes

Several factors can contribute to the triggering of DTC P0422, including:

• Faulty warm-up catalyst
• Exhaust leaks before the catalyst
• Faulty oxygen sensors
• Engine misfires or poor combustion
• Fuel system issues (e.g., incorrect fuel mixture)
• Wiring or connector issues related to the oxygen sensors

DTC P0422 seriousness

DTC P0422 is considered a moderate to serious issue. While it may not cause immediate drivability problems, it can lead to:

• Increased emissions, which can harm the environment
• Potential damage to the catalytic converter
• Failure to pass emissions testing
• Higher fuel consumption

How to diagnose DTC P0422

To diagnose DTC P0422, follow these steps:

1. Use an OBD-II scanner to confirm the presence of the P0422 code.
2. Check for any additional trouble codes that may provide more context.
3. Inspect the exhaust system for leaks before the warm-up catalyst.
4. Test the oxygen sensors for proper operation and response times.
5. Examine the warm-up catalyst for physical damage or contamination.
6. Check for any signs of engine misfires or poor combustion.

How to fix DTC P0422 step-by-step instructions

To fix DTC P0422, follow these steps:

1. Repair any exhaust leaks found during diagnosis.
2. Replace faulty oxygen sensors if they are not functioning correctly.
3. Replace the warm-up catalyst if it is damaged or ineffective.
4. Address any engine misfires or fuel system issues.
5. Clear the DTC using an OBD-II scanner and perform a test drive to verify the fix.

How to erase DTC P0422

To erase DTC P0422, follow these steps:

1. Connect an OBD-II scanner to the vehicle’s diagnostic port.
2. Turn on the ignition without starting the engine.
3. Navigate to the “Erase Codes” or “Clear DTCs” option on the scanner.
4. Confirm the action to clear the trouble codes.
5. Disconnect the scanner and start the engine to check if the code returns.

Recommended tools for OBD-II diagnostics

Explore our expert picks: The Best OBD2 Scanners for 2025

Easy-to-use Multimeter for reliable diagnostics: AstroAI Auto-ranging Multimeter

Some of the links on this page may be affiliate links, which means we may earn a small commission if you make a purchase. This helps us keep our DTC database up to date and provide valuable content for free. We only recommend products that we have tested and believe to be the best in their class.