“Just listen to your patient. He is telling you the diagnosis.” —Sir William Osler

When you’re sick, the doctor asks you questions and looks at your eyes and throat before deciding whether to run tests or prescribe medicine. Good auto shops take a similar approach. In addition to the vehicle diagnostics test, we ask the driver how the car has been running and conduct a visual inspection, too.

Without a doubt, diagnostics tools make life easier for all of us. Computers and sensors inside your car can alert you to trouble before something bad happens or significantly speed up the search for a solution. Just don’t rely on the diagnostics codes as your only source of info for auto repairs.

Before you buy an OBD-II reader and then purchase spare parts based on the error code, be aware that vehicle diagnostics have blind spots that your trusted local mechanic can see through.

One Error Code, Multiple Problems?

It’s rare for a vehicle diagnostics error code to be completely wrong. However, replacing a part or making a repair that addresses the error code might not fully fix the vehicle’s problem.

For example, a misfiring engine might produce a P0300 error code that implies a spark plug or coil needs to be replaced. But it’s possible you have a blown gasket and a bad fuel injector, too. Replacing the spark plug won’t make the engine run normally. Professional vehicle diagnostics would easily catch the other issues.

If It Ain’t Broken… Something Still Might Be Wrong

Not all vehicle diagnostics reports indicate that a part is broken or missing. Other issues to consider:

• New part not working? Some after-market parts (third-party, not OEM) fit where they’re supposed to go, but still do not work well in every make and model. You have an accurate diagnosis, but need to try a different parts brand.
• Have you made DIY repairs? Tell your mechanic if you’ve been tinkering under the hood. There’s no shame in finding out that you made a small mistake. Perhaps some wiring got re-connected in the wrong order or you failed to tighten something enough. If we know what’s been altered, we can avoid a wild goose hunt.
• Not sure what OBD-II error codes mean? Most of the error codes indicate a symptom—that is, they tell us what is failing but not why. Cars have dozens of parts involved in every function. so it might not be the most obvious reason.

Advanced Vehicle Diagnostics Tell Us More

These days, there are mobile apps that function as simple OBD-II code readers, and you can purchase your own scan tool. However, a basic code reader does not pull as much information as the enhanced vehicle diagnostics at your local auto repair shop.

Our diagnostics include detailed data about vehicle performance. This gives context to the error code. Again, it’s all about cutting to the chase without making false assumptions or ignoring what’s actually happening under the hood.

Have you been struggling with a check engine light that won’t go away or want fast auto repair in Sonoma County?

Contact us at All Around Auto Repair. Our knowledgeable mechanics will deep-dive to make accurate vehicle diagnostics and fix your car or truck correctly the first time.