OBD-II Diagnostic Trouble Code
P0420
Catalyst System Efficiency Below Threshold Bank 1
P
Powertrain
engine / trans
engine / trans
0
Generic
SAE standard
SAE standard
4
Auxiliary emission controls
20
Catalyst System Efficiency Below Threshold Bank 1
Severity · general guide
Moderate
Fix soon — usually won't strand you
Code type
Chevrolet
System
Powertrain
Model
Tahoe
Years
2007-2020