What does the service code P0420 mean
Go to: http://www.obd-codes.com/p0420 There is a lot of info on your code and the causes and repair. HTH
Its either te o2 sensor or the catalytic converter
Visit your local GMC Dealer. Unless you have over 80,000 miles on your Terrain you may be covered by the new vehicle emission control warranty. A P0420 is either going to be the downstream oxygen sensor or the catalytic converter. My experience with this code is it's going to be the catalytic converter. So check with your dealer first. HTH. -Jim
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