Can you pass emissions test with engine light on?

In most jurisdictions, you cannot pass an emissions test with the check engine light (CEL) illuminated. The light indicates a problem with the emissions system, and the testing equipment will often detect the malfunction and automatically fail the vehicle. Even if the malfunction doesn't directly affect emissions, the light itself is often enough to trigger a failure. The specific rules vary by location and the type of test performed, so it's best to check your local regulations.