check engine light 1994 e320
I'm thinking about purchasing a 1994 e320. My mechanic told me that the check engine light is a common issue in these models. He told me that the cause is usually the EGR, Wiring Harness, or Computer.
Is there any way to test to accurately tell what the cause of the problem is w/o actually replacing the parts in question?
Are there any other reasons I should not buy this automobile?