Why Is My Hyundai Tucson’s Check Engine Light On Related to the Catalytic Converter?

The catalytic converter is part of your car’s exhaust system. It helps reduce harmful emissions by converting toxic gases like carbon monoxide, nitrogen oxides, and hydrocarbons into less harmful substances carbon dioxide, nitrogen, and water vapor.

Why the Check Engine Light Comes On Related to the Catalytic Converter:
Oxygen Sensor Issues
The catalytic converter relies on oxygen sensors before and after it to monitor its efficiency. If these sensors detect that the catalytic converter isn’t working properly e.g., not reducing emissions as it should, it triggers the CEL.

Catalytic Converter Damage o r Failure
If the converter becomes clogged, broken, o r contaminated e.g., by engine misfires o r bad fuel, it can’t process exhaust gases effectively, leading to increased emissions and reduced performance. The vehicle’s computer senses this and turns on the CEL.

Engine Misfires o r Running Rich/Lean
Problems causing the engine to misfire o r run too rich too much fuel o r lean too little fuel can damage the catalytic converter. This damage will eventually trigger the CEL.

Exhaust Leaks o r Sensor Wiring Issues
Sometimes, the light might come on due to faulty wiring o r exhaust leaks affecting the sensors’ readings.

Common Diagnostic Codes Related to Catalytic Converter Issues:
P0420: Catalyst system efficiency below threshold most common code for catalytic converter problems

P0430: Same as above, but for the second bank if applicable

Other codes related to oxygen sensors e.g., P0135, P0141

What to Do:
Get a diagnostic scan done at a shop o r with an OBD-II scanner.

Check if the oxygen sensors are working properly.

Inspect for engine misfires o r fuel system problems.

Have a mechanic inspect the catalytic converter for clogging o r damage.

Ignoring a catalytic converter problem can lead to decreased fuel economy, increased emissions, and even engine damage.