New Hampshire emissions testing is required for all vehicles manufactured in 1996 or later. A vehicle inspection must be completed within 10 days of registering a vehicle and as part of the annual car registration renewal process. Emissions testing centers are located throughout New Hampshire and at authorized car dealerships. Read the sections below to learn about the importance of emissions checks in NH, when and how to obtain an exemption or waiver and what to do if your vehicle fails these important tests.

New Hampshire Emissions and Smog Check Requirements

Vehicle emissions testing in NH is required along with a safety inspection to obtain and renew car registration. Drivers must have both inspections conducted to receive a valid inspection sticker, which must be displayed on the vehicle as proof of meeting state requirements for safe vehicle operation on New Hampshire roadways.

The mechanic performing the vehicle inspection must also provide the driver with a copy of their official Vehicle Inspection Report (VIR). Inspection results are entered into a computer system that automatically reports the results to the NH DMV. When vehicle ownership is transferred, the new owner must repeat the vehicle testing process even if the original inspection sticker has not expired.

While all vehicles must pass an annual safety inspection, auto emissions testing in NH is required only for vehicles manufactured after 1996. These newer vehicles come equipped with an On-Board Diagnostics (OBD) system that monitors the performance of the engine’s major systems, including emissions. Testing must be performed on light-duty gasoline and diesel-powered vehicles with a gross vehicle weight rating (GVWR) of 8,500 pounds or less.

An OBD system inspection consists of several tests, including the following:

  • Malfunction indicator light (MIL) check during key on, engine off operation
  • Diagnostic link connector check
  • Communication with vehicle test
  • Vehicle readiness, or drive cycle check
  • MIL commanded “on” test
  • MIL light on while engine running visual check

If the vehicle fails the OBD emissions inspection, the owner has 60 days to obtain the necessary repairs and repeat the test. One warning sign that your vehicle may not meet emission test requirements is if the check engine light or the malfunction indicator light comes on and remains on. This indicates that the OBD has detected a problem and will result in an inspection rejection.

Smog Check Exemptions in New Hampshire

The only vehicles exempt from emissions checks are those manufactured before 1996. Because OBD testing is the state’s only form of emissions testing, cars without these diagnostic systems are automatically exempt.

Note that every vehicle must have an annual safety inspection, even if it is exempt from emissions testing. Antique vehicles 40 years or older receive safety inspections every 2 years during the month of April.

Out-of-State Emissions Testing in New Hampshire

If your previous New Hampshire vehicle inspection expires while you are out-of-state, you can obtain a 30-day inspection permit by submitting a request in writing. Send your request to:

NH Dept. of Safety
DMV - Registration
23 Hazen Drive
Concord, NH 03305

Emissions Waivers in New Hampshire

New Hampshire offers an Economic Hardship Waiver to qualifying car owners whose vehicles pass the safety inspection but fail the emissions inspection. It is intended to allow drivers more than 60 days to save up money for any necessary OBD repairs. To obtain a waiver application, contact the NH DMV OBD Program at (603) 227-4026.

Testing Fees in New Hampshire

The smog check price in New Hampshire is not capped or mandated in any way by the state. Each testing station sets their own fees, usually between $20 and $50 per vehicle. Call ahead to check the emission test cost at your nearest testing facility. Some may offer smog check coupons or other incentives to make testing more affordable.

Where to Perform an Emissions Check in New Hampshire

NH emissions testing locations can be found throughout the state. Smog check stations are required by the state to post a notice stating that the station is authorized to conduct inspections. Although many mechanics are certified to provide testing, your usual mechanic might not be. To be eligible for a testing waiver, you must have any OBD-related repairs completed by a state-certified mechanic.

Failing a New Hampshire Smog and Emissions Test

There are many reasons a vehicle might fail a New Hampshire smog check. Rejection reasons include:

  • The system was not ready for testing due to recent repairs or a recently disconnected battery.
  • The vehicle’s failure to communicate with the smog test system, often due to a faulty data link connector.
  • The check engine light is on.

If your vehicle fails an inspection, you must have the proper repairs performed before testing again. New Hampshire grants a one-time, 60-day repair period to allow time for necessary emissions certification diagnostics, repairs and retesting.

Last updated on Tuesday, March 10 2020.