Colorado Truck Emissions & Clean-Truck Rules
Two things here. Colorado adopted Advanced Clean Trucks, a zero-emission sales quota on manufacturers for model-year 2027 and up. Congress revoked California's waiver in June 2025, so that rule is now tied up in court and bills you nothing at the roadside. The real driver rule is the diesel opacity inspection: a diesel over 14,000 lb registered in the Front Range AIR area needs a periodic smoke test at 20% opacity. Out-of-state trucks passing through are not tested.
How Colorado handles truck emissions
Two things here. Colorado adopted Advanced Clean Trucks, a zero-emission sales quota on manufacturers for model-year 2027 and up. Congress revoked California's waiver in June 2025, so that rule is now tied up in court and bills you nothing at the roadside. The real driver rule is the diesel opacity inspection: a diesel over 14,000 lb registered in the Front Range AIR area needs a periodic smoke test at 20% opacity. Out-of-state trucks passing through are not tested.
What applies to you
- Program: Clean Truck Check
- State rule: ACT adopter, but that is a manufacturer ZEV sales quota (MY2027 and up) with no driver obligation, and its federal waiver was revoked by Congress in June 2025, leaving enforcement in limbo. The real driver rule is Colorado's diesel opacity inspection: diesels over 14,000 lb registered in the Front Range AIR area need a periodic smoke test tightened to 20% opacity. Federal EPA standards apply everywhere else.
- Penalty: Fail the diesel opacity test and Colorado blocks your registration renewal until you pass; no fixed roadside dollar fine. Federal anti-tampering penalties (about $45,000 per engine, about $5,000 per defeat device) apply on top.
- DPF / DEF: Federal EPA equipment nationwide, never delete or tamper with it
Colorado Emissions FAQ
Does Colorado have a truck emissions program?
What is the emissions rule for trucks in Colorado?
What is the penalty for an emissions violation in Colorado?
Reference information for planning, not legal advice. Traffic laws change and this can be out of date, so always confirm the current statute and obey posted signs before you rely on it. Last reviewed July 2026. Source: https://cdphe.colorado.gov/motor-vehicle-emissions/emissions-inspections-for-diesel-powered-vehicles. See our Terms & Disclaimer.
More for Colorado
Check Colorado before you roll
Live weather, closures, and hazards on one map. Free, no account.
Open Live Map →