What P0420 Means for Your 2022 GMC Canyon
A P0420 code on your 2022 GMC Canyon indicates the engine control module has detected that the Bank 1 catalytic converter isn't operating at full efficiency. The 2022 Canyon (second generation) is the final year of the previous generation and offers the 2.5-liter four-cylinder (LCV) producing 200 horsepower, the 3.6-liter V6 (LGZ) with 308 horsepower, or the Duramax 2.8-liter turbo diesel I-4 (LWN) with 181 horsepower. The V6 is by far the most popular gasoline choice.
On the 3.6L V6, Bank 1 is the rear bank. For the 2.5L four-cylinder, there's only one bank. The ECM monitors converter health through upstream and downstream O2 sensor comparisons.
Symptoms You'll Experience
- Check engine light on
- Reduced fuel economy
- Sulfur smell from exhaust
- Emissions test failure
- Normal truck operation
Common Causes on the 2022 Canyon
1. Catalytic Converter Wear
The 2022 Canyon has been in service for a few years. The 3.6L V6 produces substantial exhaust volume for a mid-size truck, and converter wear can occur with regular use. Towing with the Canyon accelerates the process.
2. Downstream O2 Sensor Failure
The post-catalyst oxygen sensor can degrade with time and heat exposure. A failing sensor is a common and relatively affordable cause of P0420.
3. Exhaust Leak
The Canyon's exhaust system can develop leaks at manifold gaskets, pipe connections, or the flex coupling after years of service and road exposure.
4. Engine Timing Chain Issues
The 3.6L V6 in the Canyon has had documented timing chain issues in some GM applications. A stretched timing chain can affect engine timing and combustion efficiency, sending partially burned fuel into the converter.
Diagnostic Steps
- Scan all codes with a GM-compatible scanner.
- Identify your engine — 2.5L I-4 or 3.6L V6.
- Monitor O2 sensor waveforms.
- Inspect exhaust system for leaks.
- Check for timing chain noise on the 3.6L V6 (rattling at startup).
Repair Cost Breakdown
- Catalytic converter replacement: $700 – $1,800 for the V6; $500 – $1,200 for the I-4.
- O2 sensor: $120 – $320.
- Exhaust leak repair: $100 – $350.
- Timing chain repair (if needed): $1,500 – $3,000 for the 3.6L V6.
Is It Safe to Drive?
Yes, P0420 is not a safety issue. Check warranty coverage — GMC's 5-year/60,000-mile powertrain warranty may still apply, and the federal emissions warranty covers converters for 8 years/80,000 miles.
Prevention Tips
- Use quality fuel
- Don't overload or over-tow beyond the Canyon's ratings
- Listen for timing chain rattle on V6 models and address early
- Follow GMC's maintenance schedule
- Replace spark plugs on time