here is a specific ban on using government vehicles in support of a candidate. Under the Public Service Act there is a requirement that public service employees use government resources properly.
6. Use of vehicles for elections-(1) A person must not use a vehicle for an activity relating to elections or to facilitate a person who intends to run for elections as a Member of Parliament.
(2) Subregulation (1) does not apply to the use of vehicle for the electoral functions, duties and powers of the Electoral Commissioner, his or her staff and any assistant working under the Commissioner’s direction after hours during elections.
(3) Any person who contravenes subregulation (1) commits an offence and is liable to a fine of 1 penalty unit.
Source: Article 6, Public Finance Management (Government Vehicles) Regulations 2015
19. Code of Conduct – An employee and a Chief Executive Officer shall:
(a) be honest and impartial; and
(b) work carefully and diligently; and
(c) treat everyone with respect and courtesy and without coercion or harassment; and
(d) comply with all laws that apply to them; and
(e) comply with all lawful and reasonable directions given to them by persons who have authority to give those directions; and
(f) disclose, and take all reasonable steps to avoid, any real or apparent conflicts of interest in relation to their employment; and
(g) use Government resources properly; and
(h) use official information only for official purposes; and
(i) act with integrity and not misuse their status or authority to seek or obtain a benefit for themselves or any other person or body; and
(j) uphold the values of the public service set out in section 17; and
(k) comply with any other conduct requirements set out in the regulations; and
(l) uphold the good reputation of the public service.
Source: Article 19, Part 4, Public Service Act 2004 consolidated as at December 2018