in my opinion he can grant loan to a co. of which he is a auditor.
because neither co law nor institute give any disqualification on such a matter.
and as such disqualification is considered by these line if you are not able to take decision.
"the relationship between the auditor and his client should be such that
firstly he himself satisfied about his client and
secondly no unbiased person would be forced to the conclusion that on an objective assessment of the circumstances ther is likely to be an abridgment (reduction) of the auditor's independence."
hence by giving loan to the company auditor is in strong position and not in weak position , so company can not dominate auditor to reduce the level of checking or to give opinion in favour of the company.