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Are Mechanics Really Charging You $$$ Just To Plug In A Computer?

While you might have seen rumours that mechanics are basically parts monkeys being told what to replace by the car itself (which is definitely true for some of us). The computer in a modern car is lot more like cooking on a camp stove instead of a brand new kitchen.

So why do so many websites claim to be able to sell you a little tool that will tell you exactly what your car needs and save you millions from scammy spanner spinners?

This argument all comes back to one of our favourite topics about cars, which is ironically computers. While we’ve talked about the compact copper computation centres in modern cars so much, there’s so much more that we’ve barely touched on.

When the computer in a modern car senses a potential problem, the computer will take note of the issue and store a short code that can be read back at a later date. For example, if the engine begins to run roughly, the computer will often store a code for an engine misfire (and can even note the cylinder that it came from).

Here’s where this story actually becomes interesting though as, while the computer may be completely right in noticing a misfire on an individual cylinder, there’s often a number of things that could cause that misfire.

An even worse example of this is when the computer senses an issue that is 3 or 4 steps downstream of the actual issue with the car.

One particular example is to look at a car that is running roughly and shows a code for a lean mixture of fuel in bank 1. This might seem like a bunch of mumbo jumbo but, our handy little computer reader (OBD2 plug) says that it’s (100%) due to a bad O2 sensor.

What this is telling us is that a sensor in the exhaust is seeing too much air in the exhaust compared to fuel and it’s definitely because of a faulty sensor.

Unfortunately, lean running codes can actually be caused by a number of things such as little air leaks and even failing fuel system components. This is what the job of a good mechanic really is, to take the information given by the car and check every system that could have an effect on it.

So is it actually possible for a mechanic to just plug in a tool and see the problem?

Well kind of yes but, in almost every situation, these codes are the equivalent of you telling the doctor that you had a fever last week and now your head hurts.

These tools absolutely have our backing though as they allow you the ability to know more about your car and to be more informed when visiting a mechanic. However, as a consumer, they also have a very big limitation and can cost you more money then they save you if you don't understand what they're telling you.


If you have any questions about this blog post, would like a second opinion from a mechanic or would like to find an honest mechanic in Brisbane, check out Kashy here.

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