What Does Code P0420 Mean on a 2024 Jeep Gladiator?
A P0420 code on your 2024 Jeep Gladiator means the ECU has detected reduced catalytic converter efficiency on Bank 1. The 2024 Gladiator continues with the 3.6L Pentastar V6 producing 285 horsepower and 260 lb-ft of torque. On a brand-new truck, this code is unusual and should be addressed under warranty.
The most common reason for P0420 on a new Gladiator is aftermarket exhaust modifications. If the vehicle is stock, a warranty-covered sensor or software issue is most likely.
Common Symptoms
- Check engine light on
- Minimal performance changes
- Slight fuel economy decrease
- Emissions test failure
- Possible faint exhaust odor
Most Likely Causes on the 2024 Gladiator
1. Aftermarket Exhaust Components
Gladiator owners frequently modify the exhaust system. Headers, catless mid-pipes, and high-flow catalytic converters are the most common P0420 triggers.
2. PCM Software Issue
On a stock vehicle, a PCM calibration update may resolve P0420. Stellantis regularly issues software updates for new model years.
3. Factory Sensor Defect
A defective downstream O2 sensor from the factory can cause false readings. This is a straightforward warranty replacement.
4. Assembly or Converter Defect
Rare but possible — an exhaust assembly issue or defective converter from the factory. Fully warranty-covered.
How to Diagnose the P0420 Code
- Determine if any exhaust modifications have been installed
- If stock, take to a Jeep dealer for warranty service
- Dealer checks for TSBs, software updates, and sensor function
- Exhaust system inspection for leaks or assembly issues
- Converter efficiency testing if other causes are eliminated
Repair Options and Costs
Warranty Repair (Stock Vehicle)
- All P0420-related repairs: No cost under warranty
Modified Vehicle
- Catalytic converter: $1,000–$2,100
- CARB-compliant components: $400–$1,200
- O2 sensor: $170–$330
- Return to stock: $200–$500 labor
DIY Considerations
Stock vehicles should go to the dealer. Modified Gladiators — owners often handle exhaust work themselves. The truck's clearance provides excellent access.
Cost Breakdown Summary
- Stock under warranty: $0
- Modified vehicle: $170–$2,100 depending on the repair
Prevention Tips
- Use CARB-compliant exhaust components if modifying
- Protect the converter with quality skid plates for off-road use
- Follow Pentastar V6 service schedule
- Avoid deep water crossings with a hot exhaust system
- Keep service records documented for warranty claims