Can I drive with a bad catalytic converter?

You can usually drive with a failing catalytic converter, but it will cause a failed emissions test and may reduce performance. A completely clogged converter can cause overheating and stalling.

What causes a catalytic converter to fail?

Common causes include engine misfires, oil or coolant burning, running rich or lean for extended periods, physical damage, and normal aging after 100,000+ miles.

P0431

Warm Up Catalyst Efficiency Below Threshold (Bank 2)

Moderatecatalyst

Overview

The P0431 code signals that the PCM has detected a warm up catalyst efficiency below threshold (bank 2) condition. This code relates to the catalytic converter, a critical emissions component that converts harmful exhaust gases into less harmful substances. Reduced catalyst efficiency typically means the converter is no longer adequately processing exhaust pollutants.

Symptoms

Check Engine Light (MIL) illuminated
Failed emissions test
Engine running hotter than normal
Rattling noise from under the vehicle

Common Causes

Contaminated catalytic converter (leaded fuel, silicone)
Faulty oxygen sensor providing incorrect readings
Oil or coolant entering the exhaust system
Rich or lean fuel mixture over extended period

Diagnosis Steps

1Connect an OBD-II scanner and read all stored trouble codes and freeze frame data
2Monitor upstream and downstream O2 sensor readings; compare switching patterns
3Check for exhaust leaks before the catalytic converter
4Inspect for engine misfires or other codes that could damage the converter
5Test the catalytic converter efficiency using a temperature gun (inlet vs outlet)

Estimated Repair Cost

$200 — $2,500

Cost varies by vehicle, location, and repair shop. Includes parts and labor.

Commonly Affected Vehicles

Honda AccordToyota RAV4Subaru OutbackChevrolet Equinox

Related Codes

P0420 P0136 P0130

More Catalyst Codes

P0420Catalyst System Efficiency Below Threshold (Bank 1)

Moderate

P0421Warm Up Catalyst Efficiency Below Threshold (Bank 1)

Moderate

P0422Main Catalyst Efficiency Below Threshold (Bank 1)

Moderate

P0423Heated Catalyst Efficiency Below Threshold (Bank 1)

Moderate

P0424Heated Catalyst Temperature Below Threshold (Bank 1)

Moderate

P0425Catalyst Temperature Sensor (Bank 1 Sensor 1)

Low

Frequently Asked Questions

Catalytic converter replacement typically costs $500-$2,500 depending on the vehicle and converter type. OEM converters are more expensive but often provide better performance and longevity.