You will need to have it programmed by a shop or dealer with ob2d programming software (Launch X431 we recommend). Your VIN# must be added to it along with linking your car key immobilizer or it will not work! This would be the case on any ECM you buy, used or new. The immobilizer and VIN# have to be added to the ECM or car will run for seconds and turn off. You do not need new keys etc - this is not true. Up for sale is a factory new OEM ECM/PCM - not a mile on it. Only fits what is listed below. No miles on it! Fits: 2005 Altima 3.5L 5 speed Transmission - with Traction Stability Control (TSC) The number on your old one must match: 23710-ZB02A 23710-ZB020 INTERNATIONAL BUYERS! PLEASE NOTE! Buyers of items shipped outside the USA are responsible for customs fees/taxes/duties and may encounter delays due to customs inspections. PLEASE be aware of this!