Having just read section 6 of the draft new rules, I see no reason at all that a
missing undertray would cause any comment UNLESS a very pedantic examiner thought it came under "modification" rules .... (: A
loose or badly fitted one that could come detached WOULD be a failure ....
https://www.mot-testing.service.gov.uk/documents/manuals/class3457/ 6.2.1 Body condition
This inspection applies to all vehicles and includes all body panels as well components such as
undertrays, spoilers and mirror housings. The inspection of bumpers is at Section 6.1.4.
A ‘body pillar’ applies only to the load carrying area of a goods vehicle.
An
unsafe modification is one that is likely to cause injury.
(a) A body panel or body component:
(i)
damaged or corroded and likely to cause injury when grazed or contacted,
or insecure
(ii) likely to become detached.
Major
Dangerous
(b) A body pillar:
(i) insecure
(ii) so insecure that load stability or security likely to be seriously impaired.
Major
Dangerous
(c) The passenger compartment in such a condition that:
(i) it permits the entry of exhaust fumes
(ii) exhaust fumes lead to a danger to health of persons on board.
(d) Body:
(i)
has an unsafe modification(ii) modification likely to adversely affect braking or steering.
Major
Dangerous
Major
Dangerous