(a)  In addition to the required safety inspection, all gasoline-powered motor vehicles which are registered or based in an exhaust emission county and which are 1975 model year or newer shall have an exhaust emission test.  This exhaust emission test is in addition to the safety inspection required in the rules in this Section and shall be administered as a part of the regular inspection only.  The exhaust emission readings resulting from the test must be at or below the standards as set forth in Paragraph (e) of this Rule or a waiver must be issued by the Commissioner of Motor Vehicles or his designated agent as specified in 19A NCAC 3D .0551.  The current year model vehicle shall be subject to the exhaust emissions inspection if presented for reinspection at anytime after the original inspection.

(b)  Vehicles which are purchased in a non-exhaust emission county and which are to be based in an exhaust emission county, shall, within 10 days of purchase, be reinspected in compliance with the Safety Equipment Exhaust Emission requirements.

(c)  The following requirements shall be adhered to by the license inspection station for calibration of the exhaust emission analyzer(s) used for state inspections.  The requirements are:

(1)           Inspections shall be performed only with an analyzer and software which has been certified by N.C. DEHNR.

(2)           All certified analyzers shall automatically require the inspection mechanic to perform a self-calibration and leak test every three days.  If the analyzer does not require a gas calibration/leak test every three days, no additional inspections shall be performed and the DMV Inspector shall be notified.

(3)           All analyzers must be equipped with two tanks of span gases in the following concentrations:

(A)          1.0% carbon monoxide, 6.0% carbon dioxide and 300 PPM Propane;

(B)          4.0% carbon monoxide, 12.0% carbon dioxide and 1200 PPM Propane.

(4)           All analyzer maintenance shall be performed according to the manufacturer's specifications and reported on a maintenance log which shall be maintained at each station.  Items to be recorded include:

(A)          all filter replacements;

(B)          water trap service; and

(C)          any replacement or repair of the probe or sample line.

(5)           Multi Point Calibration Requirements.

(A)          In high-volume stations (those performing 5000 or more tests per year), analyzers shall undergo two point calibrations each operating day and shall continually compensate for changes in barometric pressure.  Calibration shall be checked at least every four hours and the analyzer adjusted if the reading is more than 2% different from the span gas value.  Each time the analyzer electronic or optical systems are repaired or replaced, a gas calibration shall be performed prior to returning the unit to service.

(B)          In high-volume stations, monthly multi-point calibrations shall be performed.  Low-volume stations shall perform multi-point calibrations every six months.  The calibration curve shall be checked at 20%, 40%, 60%, and 80% of full scale and adjusted or repaired to meet specifications listed in 40 CFR Part 51, Appendix D(I)(b)(1) which is hereby incorporated by reference, including all subsequent editions.  This publication is available upon request at no cost from DMV Enforcement, 1100 New Bern Avenue, Raleigh, NC 27697, telephone (919) 733-7872.  The necessary additional calibration gas bottles need not be a permanent part of the analyzer, but the analyzer software must require the periodic multi-point calibration and the analyzer hardware must accept the calibration gas from an external source.

(C)          Gas calibration shall be accomplished by introducing National Bureau of Standards traceable gases into the analyzer either through the calibration port or through the probe.  Span gases utilized for calibration shall be within two percent of the required span points.

(6)           Requirements for keeping and submitting records are as follows:

(A)          Copies of the "Receipt and Statement" shall be removed from the analyzer at the time of download and filed with other business records and kept in sequence for review by the DMV Inspector during his audit.  These copies of the "Receipt and Statement" must be retained for 18 months.

(B)          A monthly report shall be submitted electronically by the analyzer on the date and time specified by the Division.  It is the station's responsibility to connect the analyzer to the proper telephone line and leave the machine properly powered for the telephone transmittal of records on the specified date and time each and every month.  Failure to comply with this requirement may result in the suspension of the station license.

(C)          Station owner(s) shall maintain the printer in a condition so that all copies of the Vehicle Inspection Receipt/Statement are clear and legible.

(d)  The procedures for inspection shall be as follows:

(1)           The vehicle's engine must be at normal operating temperature, and all accessories must be off.

(2)           The exhaust system from the engine manifold to the rear most portion of the tailpipe shall be examined to determine that the exhaust system is free from cracks, holes or dents which would restrict, reduce, allow leakage or any way prohibit the free flow of exhaust from the engine to the rear most portion of the tailpipe.  The Exhaust Emissions Test requires one analyzer probe to be inserted 10" to 16" in the end of tailpipe.  If the exhaust system is defective (leaking joints, holes, leaking seams, or leaking patches) this could interfere with an accurate exhaust emissions reading. A defective exhaust system is a failure item under the safety inspection requirements.

(3)           The inspection mechanic shall conduct the emission test with the use of an exhaust emission analyzer which has met N.C. DEHNR certification and has been approved by the North Carolina Commissioner of Motor Vehicles or his designated agent.  Standards for inspection are found in the publication, "Specification for the North Carolina Analyzer System" which is hereby incorporated by reference, including all subsequent amendments and editions.  This publication is available at no cost from the North Carolina Department of Environment, Health, and Natural Resources, Division of Environmental Management Air Quality Section, Mobile Sources, 15 North West Street, Raleigh, NC 27626, telephone 919-733-1481.

(4)           The emission's test shall be conducted using the following procedures: (All instructions provided by the analyzer must be followed):

(A)          Idle Mode Emission Test:

(i)            Analyzer must be warmed-up.

(ii)           The analyzer shall prompt the inspector to test the vehicle in as-received condition with the transmission in neutral or park.  All accessories shall be turned off and the engine running at normal operating temperature.

(iii)          The inspector shall deploy a tachometer, insert the sample probe into the tailpipe, then the test sequence shall begin.

(iv)          Pre-condition mode shall initiate when engine speed is between 2200 and 2800 RPM and continue for 30 seconds.

(v)           Idle mode test shall start when the vehicle engine speed is between 350 and 1100 RPM.  The mode shall last a minimum of 30 seconds and a maximum of 90 seconds.

(vi)          If the vehicle passes, the reported scores shall be the passing readings.  If the vehicle fails, the inspector shall proceed to the second chance test.

(vii)         Second chance pre-condition mode shall initiate when engine speed is between 2200 and 2800 RPM and continue for 180 seconds.

(viii)        Second chance idle test shall start when the vehicle engine speed is between 350 and 1100 RPM.  The mode shall last for a maximum of 90 seconds.  NOTE: The engine shall be shut off and restarted for 1981-1986 Ford Motor Company products and 1984-1985 Honda Preludes, as instructed by the analyzer.

(ix)          The pass/fail analysis shall begin after an initial time delay of 10 seconds.

(x)           The pass/fail determination is made based on a comparison of the HC and CO readings against the idle emission standards for that particular vehicle.

(B)          The analyzer shall test and disapprove a vehicle when the Carbon Monoxide (CO) or Hydrocarbon (HC) reading of the inspected vehicle is higher than the standards set forth in Paragraph (e) of this Rule.

(e)  The following chart indicates the maximum allowed Emission Standards which became effective April 1,1991:


      CO STANDARD                           HC STANDARD

VEHICLE CLASS               MODEL YEAR                             AT IDLE (0%)                              AT IDLE (PPM)

Light-duty vehicles                   1975-1977                                      4.5                                                       450

     1978-1979                                      3.5                                                       350

     1980                                                 2.0                                                       250

     1981 & later                                    1.2                                                       220

Heavy-duty vehicles                1975-78                                           5.0                                                       500

     1979 & later                                    4.0                                                       400

(f)  A challenge waiver may be issued by the Commissioner of Motor Vehicles or his designated agent.  If the owner/operator of the vehicle suspects the analyzer is incorrect, he may petition the Division of Motor Vehicles to test the vehicle in question to determine the analyzer's accuracy.  If the test determines the vehicle to be in compliance with the Emission Standards, a challenge waiver shall be issued and the Division shall immediately require an examination of the station analyzer in question and take corrective action.


History Note:        Authority G.S. 20-2; 20-39; 20-183.3;

Eff. October 1, 1994.