What Does P0420 Mean on a 2022 Chevrolet Equinox?
A P0420 code on your 2022 Chevrolet Equinox means the engine control module (ECM) has detected that your catalytic converter isn't converting exhaust pollutants efficiently enough. The 2022 Equinox runs the 1.5L turbocharged 4-cylinder LYX engine, and as an inline-four, you have a single catalytic converter on a single exhaust bank. The ECM uses the upstream and downstream oxygen sensors to monitor catalyst performance. When the downstream sensor starts mimicking the upstream sensor's switching pattern, P0420 gets stored.
The 2022 Equinox is part of the second-generation model that has been around since 2018. By now, depending on mileage and driving habits, the catalytic converter could be showing genuine wear. But the 1.5L turbo has some specific quirks that can trigger this code prematurely — oil consumption being the biggest one.
Symptoms You May Notice
- Illuminated check engine light — Often the only symptom. The light may be steady.
- Reduced fuel economy — A drop of 1-3 MPG is common when the cat is underperforming.
- Rotten egg smell at the tailpipe — Sulfur byproducts that the cat should be converting aren't being processed.
- Hesitation under heavy throttle — If the cat is partially clogged, you may feel a slight loss of power.
- Emissions test failure — P0420 is an automatic fail in states with emissions testing.
Common Causes on the 2022 Equinox
1. Oil Consumption Contaminating the Catalytic Converter
This is the big one for the 1.5L turbo Equinox. GM's 1.5L turbo engine has been widely reported for higher-than-expected oil consumption, sometimes burning a quart every 1,500 to 2,000 miles. The oil vapor passes through the combustion cycle and into the exhaust, gradually coating and poisoning the catalyst material inside the converter. If you've been topping off oil frequently between changes, this is the most likely culprit behind your P0420.
2. Failing Catalytic Converter
Even without the oil consumption issue, catalytic converters degrade over time. If your 2022 Equinox has 60,000+ miles of mostly city driving with frequent cold starts, the cat may simply be reaching the end of its useful life.
3. Faulty Downstream O2 Sensor
The post-cat oxygen sensor can fail or become sluggish, providing inaccurate efficiency readings. Heat cycling and exposure to exhaust contaminants gradually degrade these sensors. A lazy downstream O2 sensor is cheaper to replace than a catalytic converter.
4. Exhaust Leak Before the Downstream Sensor
A crack or loose gasket between the turbo downpipe and the catalytic converter lets ambient air into the exhaust stream. This extra oxygen tricks the downstream sensor into thinking the cat isn't working properly.
How to Diagnose P0420 on a 2022 Equinox
- Check your oil consumption first — Fill to the full mark, note the mileage, and check again after 1,000 miles. If you're losing more than a quart per 2,000 miles, oil burning is likely contributing to catalyst degradation.
- Scan for additional codes — Look for O2 sensor codes, misfire codes, or evaporative system codes that could point to the actual root cause.
- Monitor live O2 sensor data — Compare the upstream and downstream sensor waveforms. A healthy cat will show a nearly flat downstream signal. Rapid switching downstream means the cat is failing.
- Inspect the exhaust system — Check the turbo downpipe connection, catalytic converter flanges, and all gaskets for leaks. A smoke test is the most reliable method.
- Temperature test the cat — Using an infrared thermometer, the cat outlet should be 50-100°F hotter than the inlet when the engine is warmed up. If the outlet is cooler, the converter isn't doing its job.
Repair Options and Costs
Warranty Consideration
The catalytic converter is covered under the federal emissions warranty for 8 years/80,000 miles. Your 2022 Equinox likely still qualifies. If oil consumption is the root cause, GM may also address that under the powertrain warranty (5 years/60,000 miles). Check with your dealer before paying out of pocket.
Professional Repair
- Catalytic converter replacement — $800 to $1,600 for the 1.5L turbo Equinox. Aftermarket CARB-compliant converters are on the lower end; GM OEM parts cost more.
- Downstream O2 sensor replacement — $150 to $300 with labor.
- Exhaust leak repair — $100 to $400 depending on the location and severity.
- Oil consumption repair (piston rings) — $2,000 to $4,000 if the root cause is internal engine oil burning. Usually a warranty claim.
DIY Considerations
The downstream O2 sensor is accessible from underneath the Equinox and can be replaced with a sensor socket and basic hand tools. Catalytic converter replacement is more involved and typically requires a lift, exhaust sealant, and possibly cutting/welding if bolts are seized. Most owners should have a shop handle the cat replacement.
Cost Breakdown Summary
- Catalytic converter (parts + labor): $800 – $1,600
- Downstream O2 sensor (parts + labor): $150 – $300
- Exhaust leak repair: $100 – $400
- Oil consumption fix (piston rings, if needed): $2,000 – $4,000
Prevention Tips
- Check oil level every 1,000 miles — Don't wait for the low oil warning. Catching oil consumption early can prevent catalyst contamination.
- Use dexos1 Gen 2 or Gen 3 full synthetic oil — The correct oil specification helps minimize oil vapor and deposit buildup.
- Fix misfires immediately — Unburned fuel from misfires overheats and poisons the catalytic converter.
- Avoid excessive idling — Prolonged idling can cause the cat to cool below its optimal operating temperature, reducing its effectiveness.
- Keep up with scheduled maintenance — Fresh spark plugs and clean air filters help maintain proper combustion, protecting the cat from contamination.