What Does Code P0420 Mean on a 2019 Jeep Cherokee?
A P0420 trouble code on your 2019 Jeep Cherokee means the ECU has detected that the Bank 1 catalytic converter is not efficiently converting exhaust gases. The 2019 Cherokee (KL, refreshed) came with three engine options: the 2.4L Tigershark MultiAir inline-4 (180 hp), the 3.2L Pentastar V6 (271 hp), and the new 2.0L Hurricane turbocharged inline-4 (270 hp). All used the 9-speed automatic.
At 5+ years old with potentially 60,000-100,000 miles, the P0420 code on your 2019 Cherokee likely indicates genuine component wear, though sensor issues and exhaust leaks should be ruled out first.
Common Symptoms
- Steady check engine light
- Reduced fuel economy
- Sulfur or rotten egg smell from exhaust
- Emissions test failure
- Possible mild sluggishness if converter is restricting exhaust flow
Most Likely Causes on the 2019 Cherokee
1. Worn Catalytic Converter
At this mileage, the catalytic converter may be reaching the end of its effective life. The 2.4L Tigershark engine is particularly prone to oil consumption, which accelerates converter wear. The 3.2L V6 converter can also degrade from normal heat cycling.
2. Faulty Downstream O2 Sensor
The rear oxygen sensor can become sluggish or fail after years of heat exposure. Road salt corrosion on the sensor connector is common in northern climates.
3. Exhaust Leak
Aging gaskets at the exhaust manifold and catalytic converter flanges can develop leaks. The 9-speed automatic's vibration can loosen connections over time.
4. 2.4L Oil Consumption Issue
The Tigershark 2.4L in the Cherokee has a well-documented oil consumption problem. Oil passing through the combustion chamber contaminates and poisons the catalytic converter substrate.
How to Diagnose the P0420 Code
- Scan for all diagnostic codes — check for oil-related codes on the 2.4L
- Check for Stellantis TSBs applicable to the 2019 Cherokee
- Monitor live O2 sensor data from both upstream and downstream sensors
- Inspect the exhaust system for leaks at all gasket points
- For the 2.4L, document oil consumption rate between changes
Repair Options and Costs
Professional Repair
- Catalytic converter (2.4L): $750–$1,400 parts and labor
- Catalytic converter (3.2L): $950–$1,800 parts and labor
- O2 sensor replacement: $150–$290
- Exhaust leak repair: $120–$350
- Oil consumption repair (2.4L piston rings): $2,500–$4,000
DIY Considerations
O2 sensor replacement is a reasonable DIY job with a sensor socket and jack stands. Catalytic converter work is moderate difficulty. If oil consumption is the root cause of the 2.4L, that requires professional engine work.
Cost Breakdown Summary
- OEM converter (2.4L): $350–$850
- OEM converter (3.2L): $550–$1,200
- Aftermarket converter: $200–$550
- O2 sensor (part): $55–$160
- Labor: $200–$600
- Diagnostic fee: $80–$150
Prevention Tips
- Check oil level every 1,000 miles on the 2.4L Tigershark — add oil as needed
- Use the recommended oil grade and synthetic formulation
- Replace spark plugs at the recommended interval
- Address any engine misfires immediately to protect the converter
- Consider the emissions warranty — the 8-year/80,000-mile coverage may still apply to a 2019 model