Emissions Testing in New Hampshire

Who Needs an Emissions Test or Smog Check

For 2025, emissions testing in New Hampshire applies to passenger vehicles that use gasoline or diesel fuel, model‑year 1996 and newer (diesel 1997 or newer), with gross vehicle weight under 8,500 pounds. These vehicles must complete OBD‑II diagnostics as part of safety inspections. Older models, electric vehicles, or classic cars without OBD systems may be exempt, but state officials advise verifying any exceptions with the DMV.

How Often Tests Are Required

Testing is required annually and typically coincides with vehicle registration renewal. The first inspection after registering a new or transferred‑ownership vehicle may be valid for a shortened period based on the registrant’s birth month. Compliance remains mandatory through January 31, 2026, after which most passenger vehicle inspection requirements will end.

Where Emissions Testing Is Required

Emissions testing currently applies statewide for applicable vehicles, with no region exempt. Some areas may have variations in available facilities or scheduling practices. Drivers should consult local inspection stations or DMV resources to determine inspection access and the exact criteria that apply until the repeal date.

What Happens During the Test

During an emissions test, a technician connects to the vehicle’s OBD‑II port to perform diagnostics. The inspection includes checking the malfunction indicator light (MIL), communication with vehicle systems, readiness monitors, and whether any fault codes are active. If the vehicle fails due to a check engine light or incomplete monitors, owners have 60 days to make repairs and return for a reinspection. The technician provides a Vehicle Inspection Report that the DMV records.

Areas in New Hampshire That Require Emissions Testing

Emissions testing locations in New Hampshire are spread across the state, with multiple certified stations in cities such as Nashua, Concord, Manchester, Londonderry, Exeter, Derry, Laconia, Portsmouth, Merrimack, and Newport. Larger urban centers often offer more options and longer operating hours. Suburban and rural areas may have fewer stations, so drivers should plan ahead to locate a certified testing site. Availability may vary by region, so checking with local DMV listings or station directories can help ensure timely access to services before the inspection repeal takes effect.

How the Emissions Test Works in New Hampshire

The emissions test usually takes about 15 to 30 minutes, depending on station workload. Bring your vehicle registration and identification. First, the technician connects to the OBD‑II port to confirm system readiness and check for active fault codes or a lit check engine light. If monitors are not complete, the test may be deferred. Should the vehicle fail, you have 60 days to repair the issue and return for retesting. Common failure reasons include a lit malfunction indicator light, faulty connectors, or incomplete readiness monitors. Costs vary by testing station, so you can call ahead for estimates. After failure, the station may re‑inspect once repairs are complete, and you must pass before your registration is valid.