A vague pronoun is a pronoun whose antecedent is not clearly stated. Besides, it can lead to a misunderstanding. In this particular sentence, the personal pronoun “it” has not clear antecedent (it can be “car” or “wal”). As a result, the sentence can convey these two possible meaning:
1) The car backed into the wall but the car did not break the wall
2) The car backed into the wall but the car itself was not damages.
