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Emissions Control

Catalytic Converter

Uses precious metal catalysts to chemically convert toxic exhaust gases into less harmful emissions, reducing carbon monoxide, hydrocarbons, and nitrogen oxides by up to 90%.

$1,000 – $3,000

Total Cost

As needed (typically 100,000+ miles if properly maintained)

Replace Interval

Hard

DIY Difficulty

Schedule Soon

If It Fails

Overview

The catalytic converter reduces harmful emissions by converting toxic exhaust gases (carbon monoxide, hydrocarbons, nitrogen oxides) into less harmful substances (carbon dioxide, water vapor, nitrogen). It's expensive because it contains precious metals (platinum, palladium, rhodium).

Parts Cost

$500 – $2,500

Labor Cost

$100 – $500

Failure Symptoms

Check engine light (P0420 or P0430 codes)

Moderate

Rotten egg smell from exhaust

Moderate

Reduced engine power

Moderate

Failed emissions inspection

Moderate

Rattling noise from under the vehicle (internal honeycomb breaking apart)

Moderate

Dark exhaust smoke

Moderate

Warning Signs to Watch

Check engine light with P0420/P0430 code
Sulfur/rotten egg smell from exhaust
Rattling from underneath the vehicle
Decreased fuel economy and engine performance

Common Causes of Failure

1Engine misfires sending unburned fuel into the converter (overheating it)
2Oil or coolant entering the exhaust stream (from engine issues)
3Normal degradation of catalyst material over time
4Physical damage from road debris
5Running the engine too rich for extended periods

Prevention Tips

Fix engine misfires immediately — unburned fuel can destroy a catalytic converter in minutes
Address oil consumption issues (leaking into combustion chambers)
Don't use leaded fuel or fuel additives containing lead or silicon
Keep spark plugs and ignition system in good condition

When to Replace

Replace when diagnosed as failed (typically via P0420/P0430 codes after ruling out oxygen sensor failure). Also replace immediately if stolen. Use OEM or CARB-compliant aftermarket converters.

Catalytic Converter by Make

Toyota

Honda

Toyota and Honda catalytic converters are prime theft targets (especially Prius and Honda Element) because they contain more precious metals. Consider a catalytic converter shield ($200-$400).

Ford

Chevrolet

American trucks often have multiple catalytic converters. Aftermarket (CARB-compliant) converters are available for $200-$500 each — much cheaper than OEM.

Hyundai

Kia

Hyundai/Kia catalytic converters are increasingly targeted by thieves. Genuine OEM converters are expensive ($1,500-$2,500), but aftermarket options are available in most states.

Related Parts

Spark Plugs

Bad spark plugs cause misfires that damage the catalytic converter

Ignition Coils

Failed coils cause misfires that overheat the converter

Frequently Asked Questions

Need Catalytic Converter Replacement?

Get a free quote from a local mechanic. Average cost: $1,000 – $3,000.

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More Exhaust & Emissions Parts

Oxygen Sensor (O2 Sensor)

$100 – $350 per sensor