Vague pronoun on even though the car backed into the wall it was not damaged

"It" is the vague pronoun. The referent in the sentence is not clear. It is difficult to determine whether this pronoun refers to the car or the wall. As a result, the sentence is ambiguous and can be interpreted in two ways, one is that the car moved backwards but it was not damaged (while the wall might be damaged); the other interpretation is that the wall was not damaged even though the car hit it (maybe the car ended up with marks).