What Does P0420 Mean on a 2022 Chevrolet Traverse?
A P0420 code on your 2022 Chevrolet Traverse means the PCM has detected that the Bank 1 catalytic converter is not converting exhaust pollutants as efficiently as expected. The 2022 Traverse uses the same proven 3.6L V6 LFY engine producing 310 horsepower, paired with a 9-speed automatic. As a V6 with dual exhaust banks, your Traverse has two catalytic converters — P0420 identifies an issue with the Bank 1 converter specifically.
The 2022 Traverse is part of the second-generation model that debuted in 2018. At this point in its production run, the platform and powertrain are mature and well-sorted. The 3.6L V6 has a strong reliability reputation, so P0420 on a 2022 model with moderate mileage (say 30,000-60,000 miles) more often points to a sensor or exhaust system issue rather than a genuinely worn-out catalytic converter.
Symptoms You May Notice
- Check engine light on — Typically steady. This may be the only symptom you notice.
- Marginal fuel economy decrease — A small drop from the 18 city/27 highway EPA ratings.
- Rotten egg or sulfur odor — From the exhaust, especially at idle or low speeds.
- No obvious drivability problems — The Traverse will accelerate, shift, and handle normally.
- Emissions test failure — P0420 causes an automatic fail for OBD-II testing.
Common Causes on the 2022 Traverse
1. Faulty Downstream O2 Sensor (Bank 1)
On a vehicle that's only a few years old, the downstream oxygen sensor is a more likely culprit than the converter itself. Heat cycling, road salt exposure (in northern climates), and normal electrical degradation can cause the sensor to become sluggish or inaccurate. A bad downstream sensor mimics the waveform pattern of a failing catalytic converter, leading the PCM to set P0420.
2. Exhaust Leak Before the Downstream Sensor
The exhaust system on the 3.6L V6 Traverse includes manifold gaskets, catalytic converter flange gaskets, and pipe connections that can develop small leaks. Even a pinhole leak upstream of the Bank 1 downstream O2 sensor allows ambient air into the exhaust, throwing off the efficiency calculation. Vehicles in rust-prone regions are especially susceptible.
3. Early Catalytic Converter Degradation
While less common on a newer vehicle, the Bank 1 catalytic converter can degrade prematurely if the engine has experienced misfires, running rich, or contaminated fuel. The 3.6L V6 uses direct injection, which generally keeps combustion very clean, but ignition coil or spark plug issues can cause localized misfires that damage the converter over time.
4. Software or Sensor Calibration Issue
Occasionally, the PCM's catalyst monitoring algorithm can be overly sensitive after a battery disconnect, software update, or ECM reset. The readiness monitors may not have fully completed, or a pending calibration update from GM may address marginal P0420 threshold settings.
How to Diagnose P0420 on a 2022 Traverse
- Scan for all codes — Check for O2 sensor codes, misfire codes, and fuel trim codes. Multiple codes together help narrow down the root cause.
- Review freeze frame data — The freeze frame captured when P0420 was set tells you the engine conditions at the time — coolant temperature, RPM, load, and fuel trims. This can reveal whether the engine was running rich or lean.
- Monitor Bank 1 O2 sensor live data — Compare the upstream and downstream O2 sensor waveforms. The downstream should be nearly flat and steady. Rapid switching indicates converter failure; a completely flat signal at an unusual voltage may indicate a sensor issue.
- Check for exhaust leaks — Perform a visual inspection of all exhaust connections. A smoke test is the gold standard for finding small leaks.
- Temperature test the converter — Use an infrared thermometer to check the cat's inlet versus outlet temperature. The outlet should be hotter by 50-100°F when the engine is at operating temperature.
Repair Options and Costs
Warranty Coverage
Your 2022 Traverse should still be under GM's powertrain warranty (5 years/60,000 miles through 2027) and the federal emissions warranty covering catalytic converters (8 years/80,000 miles through 2030). Contact your Chevrolet dealer before spending any money on repairs.
Professional Repair
- Catalytic converter replacement — $900 to $1,800 for the Bank 1 converter on the 3.6L V6. OEM converters are on the higher end; aftermarket CARB-compliant units are more affordable.
- Downstream O2 sensor replacement — $150 to $350 including parts and labor.
- Exhaust leak repair — $100 to $400 for gaskets, clamps, or welding as needed.
- PCM software update — Free under warranty or $100-$150 at the dealer if not covered.
DIY Considerations
With the vehicle likely still under warranty, dealer repair is the smart choice. If you want to handle it yourself post-warranty, the Bank 1 downstream O2 sensor is accessible from underneath the vehicle with a sensor socket. Catalytic converter replacement on the Traverse requires a lift and potentially cutting rusted bolts or pipes, making it better suited for a shop.
Cost Breakdown Summary
- Catalytic converter (parts + labor): $900 – $1,800
- Downstream O2 sensor (parts + labor): $150 – $350
- Exhaust leak repair: $100 – $400
- PCM software update: $0 – $150
Prevention Tips
- Replace spark plugs at 60,000 miles — The 3.6L V6 direct injection engine relies on clean spark for efficient combustion. Worn plugs can cause misfires that harm the converter.
- Use quality gasoline — Top Tier fuel with higher detergent levels keeps the direct injection system cleaner and reduces exhaust contaminants.
- Fix engine codes immediately — Misfire codes (P0300 series), lean/rich codes, and fuel system codes should be addressed before they damage the catalytic converter.
- Inspect the exhaust system annually — Especially in salt-belt states where rust accelerates. Catching leaks early prevents false P0420 codes and further damage.
- Avoid extended idling — Prolonged idle time keeps the cat below its optimal operating temperature and loads it with uncombusted fuel residue.