If you have a code scanner, it’s important not to replace parts without an experienced diagnosis. I see people who have their own scanners, and they run the scanner on their vehicle. An error code for “transmission” comes up, and they assume they need to replace their transmission.

A code scanner is only meant to be a guide to help you know where a failure is occurring. If the code reads a transmission error, it might only be something as simple as replacing an inexpensive (when compared to the cost of replacing the transmission) shift solenoid or sensor.


That’s why it’s important to understand how to use a code scanner properly.

The Difference Between A “Code Checker” And A “Code Scanner”.

Many of the scanners in the $50-150 range merely identify the code with a short description (a code checker). They don’t properly assist in diagnosing the fault.

The $400+ scanners that I use give me much more data, and graph the various electronic parts to assist me in diagnosing your vehicle’s problem.

If a scanner can’t graph sensors or give you data lists, it won’t do a very good job in pinpointing the problem.

Also, for cheaper code checkers, manufacturers will still sell them to you as “scanners”, even though they only check codes.

Misdiagnosing Your Vehicle Can Cost You A Small Fortune!

Sometimes a customer comes in and says “I have my own scanner, what if I just tell you error code and you fix it?

I don’t recommend this approach. Here’s why:

  1. If the part I replace doesn’t fix the problem, then the customer has just wasted all of that money
  2. On top of the money, the problem now needs to be re-diagnosed, and still fixed!

A good example of this is my brother-in-law. His truck was scanned, and read an error for “EGR valve”. He spent over $450 replacing the EGR valve, and the code wasn’t even fixed. That’s because the the problem was a HOSE going to the EGR valve, not the EGR valve itself.

The hose repair cost = $70, and fixed the error code.

The unnecessary repair (due to misdiagnosis) cost over $450. And in the meanwhile, they threw a perfectly good and expensive $300 EGR valve away. Does that hurt? Yeah that’s gotta hurt juuust a little bit.

Are You A Hobbyist? Or Just Trying To Save Some Money?

Many people go to the internet to diagnose their car. The internet is full of both good and bad information, and it takes experience to weed out what’s right and what’s not.

If you’re a hobbyist who enjoys fixing cars, then you’ve probably got the time and money to make a few mistakes. But if you’re trying to save cash, doing it yourself or cutting corners could likely end up costing you even more.

The obvious conclusion, if you haven’t gathered so far, is to hire a professional for the most direct route to fixing your car. A trained mechanic knows how to read error codes for a car, and will have a technical scanner that can deliver the information needed.