P0420 on GMC ACADIA
What P0420 Means on Your GMC ACADIA
Real GMC ACADIA Owner Reports (Source: NHTSA Complaints Database)
"I was traveling at the posted speed limit of 80 mph on [XXX] in South Dakota at [XXX] and the GMC Acadia was working without any issue when all of a sudden various warnings flashed on the dashboard with one of them being power saver mode engaged."
"Owner of a 2019 GMC Acadia Denali (VIN: [XXX] , current odometer ~87,164 miles), purchased new. In early February 2026, the check engine light came on."
Data from NHTSA Vehicle Complaints Database. All reports are filed by vehicle owners directly with the U.S. Department of Transportation.
Common Causes of P0420 on GMC ACADIA
Percentages based on NHTSA complaint component analysis for this vehicle.
Complaint Trend by Year
What To Do Next
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1
Check for recalls on YOUR VIN
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if your vehicle is covered.
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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.