(a) A person, sole proprietorship, partnership, corporation, or other entity which has provided NHTSA with information under this part, which information was complete and accurate at the time the information was given to NHTSA, is not required to supplement that information in the light of after acquired information, except:

(1) The person or entity to whom the process is addressed shall supplement the response with respect to any question directly addressed to the identity and location of persons having knowledge of information obtainable under this part.

(2) The person or entity to whom the process is addressed shall seasonably amend a prior response if that person or entity obtains information upon the basis of which the person or entity knows that the response was incorrect when made or the person or entity knows that the response, though correct when made, is no longer true and the circumstances are such that a failure to amend the response is in substance a knowing concealment.

(b) The requirement to supplement information set forth in paragraph (a) of this section terminates when:

(1) The compulsory process stated that it was issued in connection with a contemplated rulemaking action, and a final rule is issued on that subject or a notice is issued announcing that the rulemaking action has been suspended or terminated.

(2) The compulsory process stated that it was issued in connection with an enforcement investigation, and the investigation is closed.

(3) The compulsory process does not state that it is issued in connection with a specific rulemaking action or enforcement investigation, and 18 months have passed since the date of the original response.

(c) This section in no way limits NHTSA's authority to obtain supplemental information by specific demands through the means specified in § 510.3.