MSPC Advisory Circular

ENVIRONMENTALPROTECTION AGENCY OFFICEOFAIRPROGRAMS MOBILESOURCEPOLLUTIONCONTROLPROGRAM A/CNo. 24 December11, 1972 Page1of 4 pages Subject: Prohibition of USCof Emission Control Defeat Devices A. PurposeThepurpose of this Advisory Circular la to notify manufacturers that EPAwill refuse to certify vehicles equipped with emission control defeat devices andto inform manufacturers as to the authority andcriteria for any suchrefusal by EPA. TheCircular also applies the policy set forth to the approval of running changer andfield fixes involving the addition of Defeat Devices to vehicles. B. Background 1. In a letter of July 12, 1972, the Administrator notified all manufacturers of light duty motor vehicles that the Agencyconsiders sensors anddevices which mayadversely affect emission control under conditions or during operations likely to occur in actual vehicle use to be inconsistent with the intent of the Clean Air Act. Specifically, it is the intent of the Act that vehicles bedesigned, built, andequipped sothat whenthey are being-used by the motoring public emissions will be reduced to the extent indicated by the prescribed standards during the period of their useful life. Thefact that it may notbe practicable to test prototype or production vehicles in order to assure the reductions under manyconditions which the vehicle will encounter doesnot mean intentional obviation of these reductions outside the parameters of the test procedure is consistent with the Act. 2. The“intent of the Clean Air Act” referred co in the letter has in part been implemented by regulations as regards test vehicles. Paragraph 85.073-9(d) requires that all emission control systems “shall befunctioning” during the Federal Test Procedure. Paragraphs 85.073-7(a) and (b) provide that emission data vehicles anddurability data vehicles, respectively, “shall bedriven...with all emissions control systems installed andoperating...” during all mileage accumulation. Theseprovisions are in the regulations to insure that emissions control systems anddevices which operate to achieve emissions reductions during emission tests operate similarly during mileage accumulation sothat their ability to achieve similar emission reductions during normal use for five years or 50,000 miles maybe reasonably assessed.ENVIRONMENTAL PROTECTION AGENCY OFFICE OFALLPROGRAMS A/CNO.24PAGE2OF4

Devices which are designed to compromisethe emission control effectiveness of any systemduring mileage accumulationas comparedwith effectiveness during emissionstesting areinconsistent with the letter andpurpose of the teat procedures. Hence, EPAcannot certify test vehicles employing suchdevices. C. Applicability

Thepolicy outlined in this Advisory Circular is effective and applicable immediately. Theprovisions of this Advisory Circular apply to certification testing beginning with the 1974modelyear andto running changesandfield fixes which would involve the addition of any Auxiliary Emission Control Device (AECD)onany modelyear vehicle. D. Definitions 1. Auxiliary Emission Control Device (AECD).AnAECDis any element of design which sensestemperature, vehicle speed, engine RPM, transmission gear, manifold vacuum,or anyother parameter for the purpose of activating, modulating, delaying, or deactivating the operation of any part of the emission control system. 2. Defeat Device. ADefeat Device is anAECD that reduces the effectiveness of the emission control system under conditions which may reasonably beexpected to be encountered in normal urban vehicle operation anduse, unless (1) suchconditions are substantially Included in the Federal emission test procedure, or (2) the needfor theAECDis justified in terms of protecting the vehicle against damageor accident, or (3) the AECD doesnot gobeyond the requirements of engine starting. E. Criteria for Determining the Acceptability of Certain AECDs 1. AnAECDis generally deemedto bea Defeat Device if it is determined by EPAto reduce the effectiveness of anemission control system:

a. In response to anyambient, underhood or passenger compartment air temperature outside the 68°- 86° Frange;

b. In response to any accessory operating condition not encountered during the Federal emission teat;.

C. After any time spanin a specific vehicle operating mode. 2. AECDs

that generally are acceptable Include those which reduce the effectiveness of anemission control system in response to:

a. Engine temperatures (as sensedbyoil or coolant temperature or someother direct indicator) which are outside the range of normal, stabilized operating temperatures;

b. Unusual engine, emission control system, or vehicle operating conditions which mayreasonably beexpected to cause damageor destruction to the engine or vehicle;C. Dmuuel engino, rrirrloa control system, or vehicle operating cdltloas vhich my ree8onably be crpected to present a ufety problem; d. The engagement of the trensmlsrion wr, es loug es no the delay Is mloyed. P. Determlnatiaa of Accepteblllty of Specific Devices 1. All AlKDr mst be described In the msnufacturer’s application for certlflcetioa. Bared upon the description of the devlca, date derived from such testing es EPApup require or conduct, end any rhowlngs made by the asnufacturer, EPAwill determine whether the device Is acceptable or whether It Is a Defeat Device. 2. The cetegorler In Section E. above, are lllurtretlve only. Therefore, the 

### lcceptebfllty of each device vi11 be deterpined on en individual basis since some dcvlccr mry not flt Into one of the catsgorier In Section g. above, others are difficult to categorize, and still other8 say have more then one purpose. If the device Is deterolned to be a Defut Device, EPAwill advise the msnufecturer in writing that test vehicles Incorporating such a device arc not eligible to provide date on the basis of which certification mry be lamed. 3. he policy stated hereln will also be aTplIed with rerpect to determinations by EPAunder 40 CFR85.073-33 and 3:. (running changer), and approvals under 40 CF’R8S.073.S(f) (carry-over datlj. 4. Any 1974 model year vehicle which ha8 :rgun mileage eccumuletlon with a Defeat Device Installed and operating is disallowed, unless the manufacturer cm show that such operation cannot reasonably be concluded to have an impact on the deterioration of the emission control system.

c. Use of Carry-over Data

If, in accordance with Advisory Circular No. 17, a menufecturcr has propored the uoe of carry-over data for 1974, such date will be accepted to the extent that the date did not originate from vehicle8 equipped with Defeat Devlcer. If Defeat Devlcea were used on 1973 model yur durability vehicles to generate date intended to be used ls the beoir for 1974 model year cettlflcetlon, testing of 1974 model yur durability vehicles which do not contain such devlcee ory be required, depending upon E2A’s judgment whether the use of the device ouy r+asonably be expected to have affected det.qK$oratios.of thc.1973 vehicle.I’. %,I” ( : ,.’ : :.’ : , ;; L_ r,

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If DefUt TkPfCU Were Ured on 1973 Podel yur MiSSiOn dew vehicle8 to generate date intended to be used es the beslr for 1974 model year certlflcation, testing of 1974 model year eml88lon date vehicles which do not coat&in such devices vlll be required,

kloblle Source Pollution Control

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