One important mistake a lot of people make is thinking they're going to fix a mechanical problem by disconnecting the battery. Fault codes set for a reason, and the goal is not to quickly erase them, cover up the problem, and hope it doesn't come back. It's to keep the problem acting up so it can be diagnosed.
The first step is always to read and record diagnostic fault codes BEFORE removing power to the Engine Computer. If the problem is intermittent and doesn't act up very often, that valuable information will be lost. Also, a lot of fault codes that indicate a circuit needs further diagnosis will stop any self-tests that rely on that circuit to compare things to. Erasing fault codes by removing power also erases fuel trim data, then the computer has to start rebuilding that in its memory. Fuel trim data can also be real useful when trying to determine which way to go with the diagnosis. That's why I want to know what the problem is before I tell someone how to lose all that information.
Tuesday, February 10th, 2015 AT 5:57 PM