P0420 Code on Your 2024 Mitsubishi Outlander
If your 2024 Mitsubishi Outlander has set a P0420 code, the engine control module has detected that the catalytic converter is not meeting its efficiency requirements. The 2024 Outlander continues with the 2.5L naturally aspirated four-cylinder engine producing 181 horsepower and a CVT transmission. Since this is an inline four-cylinder, there is only one bank.
On a 2024 model, this code should be entirely handled under warranty. Let's look at the likely causes.
Symptoms
- Check engine light on — The primary and often only symptom
- Normal vehicle operation — No drivability changes expected
- Possible minor fuel economy variation — May not be noticeable
Likely Causes for the 2024 Outlander
- ECM software calibration (35% likelihood) — The Outlander's engine management may benefit from a software update that adjusts catalyst monitor sensitivity.
- Downstream O2 sensor defect (30% likelihood) — A factory sensor anomaly can trigger false P0420 readings.
- Exhaust assembly issue (20% likelihood) — Minor factory assembly variations at gasket connections.
- Catalytic converter manufacturing defect (15% likelihood) — Rare but fully warranty-covered.
What to Do
Step 1: Visit Your Mitsubishi Dealer
Schedule a warranty service appointment. All P0420 diagnostics and repairs on a 2024 model are covered at no cost.
Step 2: Request TSB Check
Ask the dealer to check for any Technical Service Bulletins related to P0420 on the 2024 Outlander.
Step 3: Let the Dealer Handle It
The technician will use Mitsubishi's diagnostic system (MUT-III) to check codes, evaluate sensor data, and determine the repair path.
Repair Costs
All free under warranty. Out-of-warranty reference:
- Software update: $0 (warranty) / $80-$150 (out of warranty)
- O2 sensor: $0 (warranty) / $150-$300 (out of warranty)
- Exhaust repair: $0 (warranty) / $100-$400 (out of warranty)
- Catalytic converter: $0 (warranty) / $900-$1,800 (out of warranty)
Mitsubishi Warranty Coverage
Your 2024 Outlander is protected by Mitsubishi's excellent warranty:
- 5-year/60,000-mile bumper-to-bumper warranty
- 10-year/100,000-mile powertrain warranty
- 8-year/80,000-mile federal emissions warranty
DIY Advice
Do not attempt DIY repairs on a 2024 model under warranty. Let the dealer handle all work to preserve your comprehensive warranty coverage.
Prevention Tips
- Use quality gasoline — Top-tier fuel helps maintain clean combustion
- Follow Mitsubishi's maintenance schedule — Regular oil changes with 0W-20 synthetic
- Drive at highway speeds regularly — Helps the catalytic converter maintain optimal performance
- Respond to service notifications — Keep your vehicle's software current