How OBDII helps you when buying a used car
Editor's note: This post has been updated in March 2020 for accuracy and the latest information.
Purchasing a used car can be a tedious process. The chances that you make a good deal might not be so good. However, if you succeed in it, you can save a lot of money and trouble. Read more about how OBD Auto Doctor assists you to achieve this goal.
But how can you make such good a deal, how can you be sure that the car has real mileage and was properly maintained, for example? Even more, some of the problems can be hidden, such as engine and transmission problems. These hidden problems might not have come out during the test drive. The key to closing the deal successfully is to eliminate these potential problems beforehand.
First of all, one of the most beneficial means to making a good deal on buying a used car is to reveal the hidden problems immediately. OBD Auto Doctor is the tool for accomplishing this task. With our software, you can verify that the Check Engine Light (Malfunction Indicator Lamp, MIL) is really turned off, thus revealing a broken light bulb, for example.
You can also check that the Diagnostic Trouble Codes (DTCs) were not incorrectly previously turned off without fixing the real problems that caused the issues. The OBD2 software also reports the pending DTCs with a click of a button. A pending DTC is a diagnostic trouble code that is stored permanently only if the fault occurs a certain number of times. A pending DTC indicates a future issue and you should take them seriously when buying a used car. The pending trouble code will remain pending until the fault condition occurs the required number of times. In this case, the DTC will be then stored permanently. A permanent diagnostic problem will light up the MIL and requires you to fix the issue as soon as possible. On the other hand, if the malfunction does not re-occur during a set period of time, the pending DTC will be automatically cleared.
Some interesting OBD parameters when examining a car:
- Distance traveled while MIL is activated
- Number of warm-ups since DTCs cleared
- Distance traveled since DTCs cleared
- Engine run time while MIL is activated
- Engine run time since DTCs cleared
Note that the actual list of available parameters is vehicle specific and not every car supports every parameter.
Check the VIN
Secondly, you should absolutely check the car’s history records before proceeding any further. You can do this easily even on-line with Vehicle Identification Number (VIN). The VIN is a helpful identifier in this case, since a VIN is a unique for every car and it specifies the fingerprint of the vehicle. Typically, the VIN can be found by looking at the dashboard near windshield on the driver’s side of the vehicle (refer the car’s user manual for the specific location). You can also fetch the VIN with OBD Auto Doctor, and verify that the car engine has the same VIN as the physical tag. By comparing the physical VIN and the VIN reported by the OBD2 software, you can tell for sure that the car has the right engine in it.