Every California smog check term and question, plainly defined

Why do diesel smog checks cost more?

Diesel checks require specialized OBD equipment.

Per BAR (California Bureau of Automotive Repair).

This entry also has a full Q&A treatment: smoganswers.com/q/why-do-diesel-smog-checks-cost-more/

View in the A–Z glossary →

Last reviewed 2026-05-25 · Cal Smog Network canonical answer library