How do you know if your catalytic converter is bad on a Chevy Cruze?

A quick signal: a Chevy Cruze with a failing catalytic converter typically shows a lit check-engine light (often with codes such as P0420 or P0430), reduced power and fuel economy, a louder exhaust, and sometimes a sulfur-like odor or a rattling sound from under the car. If you notice these symptoms, have the vehicle inspected by a technician to confirm the cause. Driving with a bad catalytic converter can damage the engine and may fail an emissions test.

Common signs a catalytic converter may be failing

These are the most reliable indicators that the converter is not doing its job, especially on Cruze models with modern exhaust and monitoring sensors.

• Check engine light on the dash, with trouble codes related to the catalyst: P0420 or P0430 (along with related oxygen-sensor codes)


• Reduced acceleration and overall engine power; the car may feel sluggish, especially on hills or while merging


• Lower fuel economy and less efficient performance


• Rattling, metallic noise from under the vehicle, often noticeable when starting the engine or on rough roads


• Sulfur or rotten-egg smell coming from the exhaust


• Exhaust sounds louder than normal or vehicle fails an emissions test

Note that these symptoms can also be caused by issues such as a failing oxygen sensor, exhaust leak, or engine misfire, so a precise diagnosis is essential.

How a Cruze is diagnosed for catalytic converter problems

Technicians use a combination of scan data, sensor readings, and physical checks to confirm whether the cat is at fault.

• OBD-II scan to read codes and monitor live data; look for P0420/P0430 and review related engine codes that might indicate misfires or rich/lean conditions


• Inspect upstream and downstream oxygen sensors to assess sensor performance and verify proper switching behavior


• Evaluate catalyst efficiency through diagnostic tests or backpressure/temperature checks to see if the catalyst is converting exhaust pollutants


• Visually inspect the catalytic converter and heat shields for external damage, corrosion, or signs of overheating


• Perform a temperature check: a functioning cat should be hotter downstream of the catalyst; little or no temperature rise suggests a clogged or failed converter


• Rule out exhaust leaks or other component failures that could mimic cat-related symptoms

Based on the findings, a technician will determine if the catalytic converter is at fault or if another issue (such as a misfiring engine or faulty oxygen sensors) is responsible.

What to do if you suspect a bad catalytic converter on your Cruze

If diagnostics point to a failing cat, you have several paths forward. Here are common options and considerations.

• Check warranty coverage: catalytic converters are often protected under federal emissions warranties (commonly 8 years/80,000 miles) and may be subject to state-specific rules


• Address root causes first: fix misfires, sensor faults, or fuel-system problems before replacing the cat to prevent recurrence


• Replacement options: OEM (dealer) vs aftermarket; direct-fit versus universal converters; installation may require welding or clamps; price varies by model and location


• Cost expectations: aftermarket converters can range from a few hundred to around a thousand dollars or more, with labor adding to the total; OEM parts usually cost more


• Consider the long-term plan: ensure the new converter is compatible with your Cruze’s emissions system and that the shop programs any needed sensors or monitors

After replacement, verify the repair with a readiness check and, if required, an emissions test. Monitor engine performance to confirm the fix resolved the issue.

Preventing catalytic converter problems

Prevention focuses on regular maintenance and mindful driving to protect the exhaust aftertreatment system.

• Keep the engine properly tuned: replace spark plugs, ignition components, and oxygen sensors per the maintenance schedule; promptly fix misfires


• Use quality fuel and maintain a healthy air-fuel mixture to avoid unburned fuel entering the exhaust


• Don't ignore the check engine light: addressing underlying issues helps prevent cat damage


• Avoid excessive short trips; occasional highway driving helps the catalytic converter reach and maintain its operating temperature


• Inspect the exhaust system for leaks or damaged heat shields and repair as needed

Good maintenance reduces the risk of premature catalytic converter failure and helps the Cruze meet emissions standards.

Summary

A failing catalytic converter on a Chevy Cruze typically presents with a check engine light, performance and fuel-economy declines, unusual exhaust noises, and sometimes a distinct sulfur smell. A precise diagnosis—primarily using OBD-II data, sensor checks, and a physical inspection—will confirm whether the cat is at fault. If replacement is necessary, address root causes and choose a compatible option (OEM or aftermarket) while considering warranty coverage and costs. Regular maintenance and attentive driving can prolong the converter’s life and maintain emissions compliance.

How do you know if your catalytic converter is bad on a Chevy?

Symptoms of catalytic converter failure in a Chevy include decreased engine performance, a rotten egg or sulfur smell, a glowing red catalytic converter, and a check engine light with codes like P0420. You may also experience sluggish acceleration, poor fuel economy, and excessive heat from under the vehicle.
 
Engine performance and driveability

• Sluggish acceleration: The engine may feel less powerful and take longer to get up to speed. 
• Poor fuel economy: You may notice you have to fill up the gas tank more frequently. 
• Engine hesitation or stalling: The engine might hesitate or struggle to run smoothly, especially under load. 
• Difficulty starting: A clogged converter can make it harder to start the engine. 

Smells and heat 

• Rotten egg or sulfur smell: This is a very common and distinct sign that the converter is not properly processing exhaust gases. 
• Excessive heat: You may feel more heat coming from under the vehicle, as the converter can get extremely hot when failing. 
• Glowing red converter: In severe cases, the converter can get so hot that it glows red, especially when the engine is under load. 

Warning lights and codes

• Check Engine light: The car's computer can detect a faulty converter, triggering the "Check Engine" light. 
• Diagnostic Trouble Codes (DTCs): A scanner can read specific codes, most commonly P0420 (Catalyst System Efficiency Below Threshold), which directly indicates a converter issue. 

Other indicators

• Rattling noise: The internal structure of the converter can break apart and rattle, especially when the vehicle is running or hit. 
• Black smoke: If the converter is failing, you might see black smoke coming from the tailpipe. 

What are three signs of a bad catalytic converter?

If you notice any of these symptoms, it's best to take your vehicle to a specialist for inspection.

• Rattling Noise.
• Blue Emissions.
• Reduced Engine Performance.
• Low Gas Mileage.
• "Check Engine" Light Comes On.
• Sulfur Smell from Exhaust.
• Failed Emissions Test.
• The Bottom Line.

What is the problem with the catalytic converter on a 2014 Chevy Cruze?

Reason For This Recall: On certain 2013-2014 model year Chevrolet Cruze and Sonic vehicles equipped with a 1.8L engine, cracking of ceramic components internal to the catalytic converter may occur as a result of higher than anticipated exhaust temperatures.

How much does it cost to replace a catalytic converter on a Chevy Cruze?

between $1,045 and $1,482
The average cost for a Chevrolet Cruze Catalytic Converter Replacement is between $1,045 and $1,482.