What should be done if smoke is visible at the tailpipe during a diesel inspection?

If smoke is visible at the tailpipe during a diesel inspection, it indicates that the engine is not operating as expected and is likely emitting pollutants beyond acceptable levels. Visible smoke can point to various issues, such as incomplete combustion, excessive fuel consumption, or problems with the fuel injection system. Since the primary goal of the smog check is to ensure that vehicles meet emission standards to protect air quality, the presence of visible smoke serves as a clear indication that the vehicle is not in compliance with those standards. Therefore, the inspection must fail, necessitating corrective actions to address the underlying issues before the vehicle can be considered roadworthy and environmentally compliant.

In this context, the other options do not address the seriousness of the emissions problem effectively. Passing the inspection without addressing the visible smoke would undermine environmental regulations, while suggesting that additional tests are needed could delay necessary repairs instead of ensuring immediate compliance. Lastly, escalating the issue may not be required unless there are extenuating circumstances beyond the immediate failure due to visible smoke.