What Does P0420 Mean on a 2022 Dodge Hornet?
A P0420 code on your 2022 Dodge Hornet indicates that the Bank 1 catalytic converter isn't cleaning exhaust gases as efficiently as expected. The 2022 Hornet — Dodge's entry into the compact SUV segment — is powered by a 2.0L turbocharged four-cylinder engine producing 268 horsepower in the GT trim, or a 1.3L turbocharged four-cylinder plug-in hybrid producing a combined 288 horsepower in the R/T trim. The turbo four-cylinder engine in the GT model is derived from the Alfa Romeo Tonale platform and shares many components.
Since the Hornet is a relatively new model for Dodge, understanding the specific engine and exhaust layout is important for accurate diagnosis. Let's walk through the possible causes and solutions.
Symptoms to Watch For
- Check engine light on — The most common indicator
- Slightly reduced fuel efficiency — You may notice a small MPG drop
- Faint sulfur smell — From the exhaust area
- Normal performance — Drivability typically remains unchanged
- Failed emissions test — Automatic failure in states that test
Common Causes on the 2022 Hornet
1. Downstream O2 Sensor Issue
On a vehicle this new, a faulty downstream oxygen sensor is a leading suspect. The sensor monitors the catalytic converter's output and can produce false readings if it's defective or contaminated. The Hornet's turbocharged engine produces more exhaust heat than naturally aspirated engines, which can stress sensor components.
2. PCM Software Calibration
As a new model, the Hornet may have PCM calibration settings that need refinement. Stellantis (Dodge's parent company) regularly releases software updates that adjust catalyst monitoring thresholds. Check with your dealer for any available updates.
3. Catalytic Converter Defect
Being a first-year model, the Hornet's catalytic converter may have manufacturing inconsistencies. The turbo engine's close-coupled catalytic converter operates at very high temperatures, and any deficiency in the catalyst coating can show up as poor efficiency.
4. Exhaust Leak Near Turbo or Converter
The turbocharged engine's exhaust path includes the turbocharger, downpipe, and catalytic converter in close proximity. Any leak at the turbo outlet gasket, downpipe connection, or converter inlet can introduce air that affects O2 sensor readings.
Diagnostic Steps
- Dealer TSB check — As a newer model, TSBs are especially important. Have your dealer scan for any updates specific to the Hornet.
- Full code scan — Look for any additional codes that may accompany the P0420.
- O2 sensor data analysis — Compare upstream and downstream sensor patterns to evaluate converter efficiency.
- Exhaust system inspection — Check all connections from the turbo to the downstream sensor for leaks.
Repair Costs
- Catalytic converter replacement: $1,000 – $1,800 (likely warranty-covered)
- Downstream O2 sensor: $120 – $280 (likely warranty-covered)
- PCM software update: $0 – $150 (typically free under TSB)
- Exhaust leak repair: $100 – $350 (likely warranty-covered)
Is It Safe to Drive?
Yes, your 2022 Hornet is safe to drive with a P0420 code. The code is purely emissions-related and doesn't affect safety or basic drivability. Since your Hornet is still under warranty, take it to the dealer for a likely no-cost repair.
Prevention Tips
- Use quality fuel — The turbocharged engine benefits from premium or at minimum Top Tier regular gasoline
- Follow the maintenance schedule — Regular service prevents issues that can damage the converter
- Don't ignore other codes — Address any engine-related codes promptly
- Let the turbo cool down — After hard driving, idle for a minute before shutting off to protect turbo and exhaust components