Which term describes normal wear or deterioration affecting the operation of a emission control component?

• A. Not Applicable
• B. Modified
• C. Tampered
• D. Defective

Answer: (D)

Normal wear or deterioration that prevents an emission control component from operating as designed is described as defective. This term signals that the part has aged or degraded to the point where it no longer meets the required performance, even though there wasn't any intentional alteration. It’s about functional failure due to wear, not about changes you made to the part.

Not Applicable would be used when the rule doesn’t apply to the situation, Modified would mean you changed the part from its original form, and Tampered would imply intentional manipulation to defeat the system. In the case of wear causing a loss of proper function, defective is the appropriate label because it directly reflects reduced performance from aging or deterioration.