Your 2022 Sorento's check engine light with P0420 points to catalytic converter efficiency problems. The hesitation you're feeling suggests something more than just an aging catalyst—there may be an underlying condition affecting both performance and converter health.
Understanding P0420
The P0420 code means "Catalyst System Efficiency Below Threshold (Bank 1)." The engine computer compares readings from the front and rear oxygen sensors. A healthy catalytic converter produces significantly different readings. When they're too similar, the catalyst isn't cleaning exhaust properly.
Why Hesitation Accompanies P0420
Hesitation combined with P0420 suggests related issues:
- A rich or lean condition overworking the catalyst
- Misfires that damaged the catalyst and affect performance
- Exhaust restriction from a failing converter
- Sensor issues causing incorrect fuel mixture
Common Causes
- Degraded catalyst - Substrate has broken down over time
- Contaminated catalyst - Oil or coolant entered and damaged it
- Faulty rear O2 sensor - Giving false efficiency readings
- Exhaust leak - Air entering skews sensor readings
- Upstream problem - Rich/lean condition or misfires killed the catalyst
Don't Just Replace the Cat
If something damaged your catalytic converter, replacing it without fixing the root cause will damage the new one too. Look for:
- Oil consumption issues
- Coolant leaks into combustion
- Chronic rich or lean fuel trims
- Recurring misfires
Diagnostic Steps
- Check for additional codes—misfires or fuel trim issues
- Compare front and rear O2 sensor waveforms
- Inspect for exhaust leaks before the rear sensor
- Temperature test catalyst (outlet should be hotter than inlet)
- Check for oil consumption or coolant loss
Repair Costs
- Rear O2 sensor: $150-$300
- Exhaust leak repair: $100-$400
- Catalytic converter: $800-$2,500
Federal emissions warranty covers the catalytic converter for 8 years/80,000 miles. Your 2022 should qualify.