I purchased this Acton scanner 2 years ago when our older vehicle was repeatedly showing its MIL (Malfunction Indicator Lamp). I was able to clear the code immediately. When the MIL illuminated again later, I was able to track down the problem (O2 sensor heater trouble)and correct it by reseating the connector. Later, I used the scanner to diagnose which cylinder was misfiring. By tapping on that cylinder's fuel injector, I was able to correct the misfiring. Again, the Acton cleared the MIL display.