P0420 on Chevrolet Traverse
Catalyst System Efficiency Below Threshold Bank 1
Methodology: Reviewed against the SAE J2012 generic DTC definition and NHTSA owner-complaint patterns, then scoped to Chevrolet Traverse context without treating complaints as confirmed diagnoses.
Sources: SAE/OBD-II definitions, manufacturer service information, and public reliability reports (including NHTSA where applicable).
- SAE J2012 Diagnostic Trouble Code Definitions — Generic diagnostic trouble code definition reference for P0420.
- NHTSA recalls, complaints, and manufacturer communications — Used to check public owner complaint context, recall status, and safety-related manufacturer communications by VIN or vehicle.
Limits: Guidance is informational and may not match every model-year or revision. Confirm with the official manual and diagnostics before replacing parts. For safety-critical or electrical work, use a qualified technician.
What P0420 Means on Your Chevrolet Traverse
P0420 is a diagnostic trouble code indicating: Catalyst System Efficiency Below Threshold Bank 1. This code relates to the emission controls system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.
Real Chevrolet Traverse Owner Reports
Source: NHTSA Complaints Database
"Recently bought this traverse 2010 ltz from a private owner after 200 miles on the road the check engine light triggered a few codes p0008-p0017-p0420, upon extensive diagnostics at four different places."
"My vehicle was getting a check engine code #P0420, took to my GM dealer for service on [XXX]. RK Chevrolet in Virginia Beach, VA. Was told the error was caused by the mounting bracket on the front exhaust pipe had separated from the pipe, resulting in a hole in the pipe."
"2019 chevy traverse check engine light came on then went off for a couple of weeks. The engine light came back on and I took it in to dealership. They found code p0420 which is fail code catalytic converter."
"The contact owns a 2020 Chevrolet Traverse. The contact stated while driving 45 MPH, the vehicle jerked, with an abnormal sound coming from underneath the vehicle. In addition, the contact stated the vehicle failed to accelerate as intended while depressing the accelerator pedal."
"Engine light came on couple weeks ago. Code is p0420 so I did some research and inspected the exhaust system and found the weld on the support bracket of the exhaust pipes was cracked and wore a hole between the pipe and the bracket."
All reports filed by vehicle owners directly with the U.S. Department of Transportation.
📊 Complaint Trend by Model Year
Common Causes on Chevrolet Traverse
Based on NHTSA complaint component analysis for this vehicle.
What To Do Next
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1
Check for recalls on YOUR VIN
Go to nhtsa.gov/recalls and enter your VIN. If your vehicle is covered, repairs are free.
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2
Get a proper diagnosis
A code alone doesn't tell you the exact failed part. A diagnostic at a shop ($50–$150) pinpoints the root cause before you spend money on parts.
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3
Compare repair quotes
Get 2–3 quotes. Dealer vs. independent shop prices often differ 30–50% for the same repair.