2007 Chevrolet P0420: What It Means & Is It Safe to Drive?
P0420 on the 2007 Chevrolet: Catalyst System Efficiency Below Threshold (Bank 1). Here's what it means, what usually causes it, what repairs typically cost, and whether it's safe to keep driving.
What this code means
The downstream oxygen sensor detects that the catalytic converter is not storing or converting exhaust properly. This is one of the most common check engine codes.
Common causes on the 2007 Chevrolet
- Failed or aging catalytic converter
- Faulty downstream oxygen sensor
- Exhaust leak before or after the catalyst
- Engine misfire or rich/lean condition damaging the catalyst
Symptoms
- Check Engine Light on
- Often no drivability issues
- Possible failed emissions test
- Rotten egg smell in some cases
Typical fixes
- Replace catalytic converter
- Replace oxygen sensor(s)
- Repair exhaust leaks
- Fix underlying fuel/ignition issues first
Repair cost range
For a 2007 Chevrolet, repairs for P0420 typically fall between $400 and $2400, depending on the root cause and labor rates in your area.
Known issues on Chevrolet
Chevrolet P0420 on the 5.3L V8 is heavily linked to AFM (Active Fuel Management) lifter failures—a misfiring cylinder from a collapsed lifter dumps unburned fuel into the exhaust and destroys the cat quickly. Fix AFM issues first. On Equinox 2.4L (2010–2017), oil consumption via piston rings is a known defect that poisons the catalyst; GM issued a settlement on this. Cruze 1.4T has a small close-coupled cat that clogs early on high-mileage engines with oil consumption.
Most commonly affected models