2015 Chevy Silverado P0128 Code Thermostat p0128 smog failed test temperature regulating coolant below Failed a smog test Failed a SMOG test - Maintenance/Repairs - Car Talk Community Failed a SMOG test - Maintenance/Repairs - Car Talk Community Check Details ← 2016 Jeep Cherokee P0128 Code 2018 Dodge Grand Caravan Code P0128 → Share with friends Link copied