Plugs into the Intake Air Temp sensor, so it'll lie to the ECU about what the temperature is, and the ECU will change the fuel it's providing to keep what it thinks is the correct Fuel/Air mix. IMHO It's not much more than a fancier version of the ebay sellers that stick resistors in line with the sensor and sell a 2p (or 2 cent in your case ) component for many £'s/$'s.
ETA... come to think of it it can't be any more than a resistor or other passive circuit. If it's only got 2 connections, then unless it's got a very clever parasitic power supply built in then it's not powered - therefore can't be a microchip of any description.