Your engine tester is of no use to you!
The importance of diagnostics is underestimated, oh so underestimated! Why?! Because people don't want to understand that diagnostics isn't just reading error codes, it's finding faults!
The importance of diagnostics is underestimated, oh so underestimated! Why?! Because people don't want to understand that diagnostics isn't just reading error codes, it's finding faults!