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Automotive scan toolAutomotive scan tool or car code reader. This is my second article on the subject of why everyone should have one. At the bottom of this short page is a link to pictures and reviews of scanners I own. Connecting the auto scan tool to your vehicle and pulling out the codes and then resetting the light is your auto repair shops favorite job. They don't have to get dirty or bust their knuckles, and it pays very well. Automotive scan tools are cheapI would like to mention that all of the scan tools and car code readers today come with in-depth operational manuals that will easily explain how to pull and erase codes. As I mentioned in my last article, most codes are intermittent and clearing and a erasing the codes are all that needs to be done. But if you erase the code and it immediately comes back or comes back within 24 hours of vehicle operation this is considered a hard failure code. Let me give you an example of a hard code failure.
In this next example of using an automotive scan tool and reading scan tool data. I'm going to give you a very common code that you could find set in the computers memory. I come across the oxygen sensor voltage low or high code all the time. Many mechanics when they find this code just want to go ahead and replace the oxygen sensors. This may not be the right thing to do. When you pull this code up on your automotive scan tool, the first thing you want to do is reset the code and see if it returns. If the check engine light has come back on and this code has reset the second thing you want to do is read the data stream for the oxygen sensors. Reading scan tool data for this code using the automotive scan tool is a lot easier than you would think. oxygen sensor operation
The oxygen sensor voltage should vary quickly from about 200 to 800 mV. The rule of thumb is that the voltage should go below 500, and above 500 mV in an even pattern.
If you should run across an oxygen sensor that has a fixed voltage or a voltage that is always below 500. You want to check the wiring to the sensor. The oxygen sensor wiring is underneath the vehicle and is easily damaged. Another reason that you may have a low or fixed voltage is that the oxygen sensor is reading correctly, but the exhaust gases are not in the proper range. This could relate to a problem in the fuel system management program. As in that the exhaust gases are actually lean or rich due to a failure of a fuel system component. As an example, a leaky fuel injector, a vacuum leak, or a misfire condition. So to clarify my point, if you set an oxygen sensor code this does not always indicate that the oxygen sensor needs to be replaced. What the oxygen sensor code does indicate is that diagnosis is necessary. When does an oxygen sensor need replacing
The exception to this rule is if your vehicle has extremely high mileage. Oxygen sensors start to lose their accuracy at around 100,000 miles of vehicle usage. Again, this does not mean that the sensor needs to be replaced, but it is an indication that the sensor operation should be checked carefully. Using the automotive scan tool can be interesting and fun. Reading scan tool data can be a great learning experience. Another bonus is that plugging in the tool and reading the data is a clean operation. It will not be cover you with grease, you will not bust your knuckles, and it is almost impossible to injure yourself performing this operation. Help this car site grow and find your way back with a
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