What the smog test result means
After a scan, the result tells you if the car needs a smog check, and which test.
The three answers
- Needs a smog check: the car needs a test. The result names the test.
- Exempt: the car does not need a smog check, and the result says why. For example, it is electric, or it is a 1975 or older model.
- Can't determine: we could not tell from the car’s details. Check it on the analyzer.
The test types
- OIS test: plugged into the car’s OBD port, no tailpipe probe.
- ASM test: a tailpipe test on the dyno, used in Enhanced program areas.
- Two-speed idle test: a tailpipe test at idle and at about 2,500 rpm, no dyno.
For older cars, ASM or TSI depends on your program area. Set it in Settings, under Station, so the result picks the right one.
Your analyzer has the final word. When the result says Check on the analyzer, go by what the BAR analyzer tells you. SmogScanner does not connect to the analyzer.
The car details come from the U.S. government’s car database (NHTSA). The result is a guide. BAR and the DMV are the official sources.
The rules behind each answer are in our guides: test types and exemptions.