Catalytic Converter Replacement - Overland Park, Merriam, Shawnee & Olathe, KS

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Catalytic Converter Replacement

Expert Catalytic Converter Replacement in Overland Park, South Overland Park, Merriam, Shawnee & Olathe, KS.

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ASE-Certified TechniciansRoot-Cause Diagnosis First5-Yr / 50k-Mile WarrantyFree Check-Engine-Light Scan

OverviewFig. 02

A catalytic converter rarely fails on its own — so replacing one without finding why it failed is a good way to buy two of them.

The catalytic converter is the part of the exhaust that cleans up what the engine burns, using a honeycomb catalyst to convert harmful gases into far less harmful ones. It's a major contributor to how cleanly your vehicle runs. When it clogs, overheats, or the catalyst breaks down, you'll often see a check-engine light, feel a loss of power, or hear a rattle from underneath.

Here's the part other shops skip: a converter almost always fails because of something else — a misfire, an oil or coolant leak feeding the exhaust, or a rich fuel mixture that cooked it. If we replace the converter without fixing that underlying problem, the new one is on the same path to failure. We diagnose the root cause first, then replace.

A catalytic converter rarely fails on its own — so replacing one without finding why it failed is a good way to buy two of them.

A check-engine light with a P0420 code
A rattle from underneath the vehicle
Noticeable loss of power or poor acceleration
A rotten-egg or sulfur smell

Confirm the converter has failed
Identify and address the root cause
Remove the old converter
Install a quality replacement
Transfer or replace oxygen sensors

A catalytic converter is an expensive part, and replacing one that failed because of an upstream problem just sends the new one toward the same fate. A misfire that dumps raw fuel into the exhaust, an engine burning oil or coolant, or a chronically rich mixture can all destroy a converter from the inside.

Symptom Explorer

Signs of a failing catalytic converter

These commonly point to a converter problem, but several overlap with other exhaust and engine faults — a scan and inspection confirm the cause before any part is replaced.

A note on symptoms — These signs point toward a likely cause — they are not a diagnosis. A professional inspection confirms what is actually happening before any parts are replaced.

The P0420 code means the computer sees the converter working below the efficiency it expects, based on the downstream oxygen sensor. It often points to the converter, but it can also be set by a sensor fault or an exhaust leak, so it needs to be confirmed, not assumed.

If the ceramic catalyst inside breaks apart, the loose pieces can rattle, especially at idle or over bumps. This likely means the converter's internals have come apart and should be inspected promptly.

A clogged converter restricts exhaust flow, which can make the engine feel sluggish and strained, especially at higher speeds. A back-pressure check helps confirm whether the converter is the restriction.

A sulfur odor from the exhaust can indicate a converter that's struggling or being overloaded by a rich fuel mixture. Because the cause may be upstream, it's worth diagnosing rather than only replacing the converter.

Since cleaning emissions is the converter's whole job, a degraded one can cause a failed test even when the car seems to run fine. The scan and readings usually show whether the converter or something feeding it is responsible.

Why Diagnostics Matter

Finding the root cause before you replace it

We confirm the converter is actually bad — checking back-pressure and oxygen-sensor data — and then look upstream for whatever damaged it. Fixing that cause first is what protects your investment in the new converter.

01P0420 verified against sensor data, not assumed
02Back-pressure checked to confirm a clog
03Misfires, oil, and coolant intrusion ruled out
04Fuel mixture and upstream sensors reviewed

What's Included№ 05 — Scope of Work

What the job involves

A proper converter replacement pairs the new part with a fix for whatever caused the original to fail.

Confirm the converter has failed

We verify with a scan, oxygen-sensor data, and a back-pressure check rather than replacing on the code alone.

Identify and address the root cause

Before fitting a new converter, we find and recommend fixing what damaged it — a misfire, an oil or coolant leak, or a rich mixture — so the replacement isn't put on the same path.

Remove the old converter

The failed converter is separated from the exhaust, whether it bolts in or is welded, with care taken around the surrounding exhaust and sensors.

Install a quality replacement

A converter that meets the correct specification for your vehicle is fitted with new gaskets and hardware and sealed properly to the exhaust.

Transfer or replace oxygen sensors

The downstream sensor is reinstalled or replaced as needed so the computer can properly monitor the new converter's performance.

Clear codes and verify efficiency

We clear the code, run the engine, and confirm on live data that the new converter is doing its job and the light stays off.

When To Come In№ 06

When converter replacement is the right call

Watch for

A confirmed P0420 that returns after sensors are ruled out
A rattle from a broken-up internal catalyst
A measurable exhaust restriction and power loss
A failed emissions test tied to converter efficiency

If you wait

A clogged converter chokes the engine and saps power
Loose internal pieces can restrict flow further
Replacing without fixing the cause risks a repeat failure
Emissions stay out of compliance until it's addressed

Stay ahead

Fix misfires and leaks promptly to protect the converter
Keep up with the fueling and ignition maintenance that affects it
Have a P0420 diagnosed, not just cleared
Ask for a free check-engine-light scan to start

QuestionsFAQ

Frequently asked questions

P0420 means the engine computer sees your catalytic converter operating below the efficiency it expects, judged by the oxygen sensor after the converter. It often indicates a worn-out converter, but it can also be caused by a faulty sensor or an exhaust leak. We confirm which before recommending the expensive part.

Because a converter almost never fails without a reason. A misfire, an engine burning oil or coolant, or a rich fuel mixture can overheat and destroy the catalyst inside. If we install a new converter without fixing that cause, it's headed for the same failure — so finding the root cause first protects your investment.

It depends on how it failed. A slightly degraded converter may let you drive while you plan the repair, but a clogged or broken-up one restricts exhaust flow, which can starve the engine of power and, in severe cases, stress other parts. Have it diagnosed so we can tell you whether it's safe to wait.

Yes — qualifying parts and labor are backed by our 5-year/50,000-mile nationwide warranty, honored at participating shops across the country. We'll go over the coverage that applies to your specific repair when we write the estimate.

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