I get it, diagnostics tools plug into the vehicle, tell you everything you need to know and in many cases even guide you to a vehicle fix. OTC makes several scan tools that do just that; and they work great. They help get a vehicle back on the road quickly and provide a ton of information. But sometimes you have to get back to the basics of auto repair, and use your head before letting a tool think for you.
Take a vehicle with a potential Mass Air Flow sensor issue. The dash shows a warning light, your scan tools says it’s a MAF issue, you replace the sensor, clear the code and send the customer on their way. On many vehicles this is a problem, a quick fix and you beat the flat rate. That is, until the customer returns because the light comes on again.
A scan tool will keep telling you it’s a MAF issue, but replacing the sensor hundreds of times will never fix the real problem, because it may not be electrical or component-based.
I’ve seen this happen, with hours spent diagnosing and “repairing” the issue without a simple visual inspection of the system. In cold climates, mice can nest near a vehicle’s heater core or air intake system, especially in vehicles that are stored over winter. Mice will nest where they can fit, and small, enclosed spaces are ideal homes in the winter.
You can get so caught up in the ease of using a scan tool that you forget the basics, like checking the air filter and intake for blockage.
One of my experiences lies in a buggy rear window defroster, and a simple fix that took too long to discover. After tearing off vehicle panels, checking fuses and electrical connections, I thought to check the ground. A wire brush, a bit of cola and the defroster was working a few minutes later.
So if a scan tool doesn’t give you the right answer right away, go back to what you did as a kid just learning how to work on cars – take stuff apart, open it up, get a better look, and you may just find and fix the problem.
