What Does P0420 Mean on Your 2022 Mitsubishi Eclipse Cross?
A P0420 code on your 2022 Mitsubishi Eclipse Cross means the engine control module has determined that the catalytic converter on Bank 1 is not converting exhaust pollutants efficiently enough. The 2022 Eclipse Cross uses a 1.5L turbocharged four-cylinder engine (4B40) producing 152 horsepower, paired with a CVT transmission. Since this is an inline four-cylinder, Bank 1 covers the entire engine.
The Eclipse Cross's smaller turbocharged engine operates at relatively high temperatures for its displacement, which factors into catalytic converter health. Let's examine what might be triggering this code.
Common Symptoms
- Check engine light illuminated — The primary P0420 indicator
- Slight decrease in fuel economy — Perhaps 1-2 MPG below your normal average
- Sulfur or egg smell from exhaust — Can indicate catalyst material breakdown
- Normal driving behavior — The Eclipse Cross typically drives fine with this code
- Emissions test failure — Will fail inspection with an active code
Common Causes for the 2022 Eclipse Cross
The 1.5L turbo engine produces concentrated exhaust heat through a small-diameter catalytic converter:
- Catalytic converter degradation (40% likelihood) — The 1.5T engine's turbocharger generates high exhaust gas temperatures, and the compact catalytic converter receives this heat directly. City driving with frequent acceleration cycles increases thermal stress.
- Downstream O2 sensor failure (25% likelihood) — The oxygen sensor monitoring converter efficiency can drift or fail, producing false P0420 readings.
- Exhaust leak at turbo downpipe (20% likelihood) — The connection between the turbocharger and the catalytic converter is a common leak point, especially with thermal cycling.
- Rich running condition (15% likelihood) — Issues with the direct injection system or turbo wastegate can cause excess fuel in the exhaust.
Diagnostic Steps
Step 1: Full Code Scan
Scan for all stored, pending, and history codes. Look for fuel trim, misfire, or O2 sensor codes that could reveal the root cause.
Step 2: O2 Sensor Data Review
Monitor upstream and downstream O2 sensor data. The downstream sensor should hold a steady voltage between 0.6-0.8V. Erratic readings suggest a sensor problem or failed converter.
Step 3: Exhaust Inspection
Check the turbo downpipe connections and catalytic converter for leaks, damage, or deterioration. A smoke test can reveal small leaks.
Repair Options and Costs
The Eclipse Cross is an affordable compact SUV, and repair costs reflect this:
- Catalytic converter replacement: $800 - $1,600 (parts and labor). Aftermarket converters are available and can reduce costs significantly.
- O2 sensor replacement: $130 - $280 (parts and labor)
- Exhaust leak repair: $100 - $350
- Fuel system repair: $200 - $450
DIY Feasibility
The Eclipse Cross is moderately DIY-friendly. The O2 sensor is accessible from underneath the vehicle. The catalytic converter is more challenging but possible for experienced home mechanics. The 1.5T engine bay is compact but not as cramped as some competitors.
Prevention Tips
- Use quality gasoline — Top-tier fuel helps the turbo engine run cleanly
- Follow Mitsubishi's oil change intervals — Use 0W-20 synthetic oil as specified
- Avoid excessive idling — Let the catalytic converter reach operating temperature
- Address engine codes promptly — Misfires and fuel issues can quickly damage the converter