How to replace ecu in 1999 Nissan Maxima? My mechanic told me I need a new ecu, the car still runs good but the check engine light is on. So my first question is if it can be possible for the car to need a new ecu and still run pretty good? and my second question is will it be possible for me to buy an ecu from eBay and just install it my self? I did some research and I read that by disconnecting the battery removing the ecu installing the new one and connecting the battery would do the trick. Any help would be good.
Answer: Do you know what trouble code? There are many codes even some caused by fuel tank and motor mounts that will not make the car run bad. ECM is on top the drive tunnel under the heater box it is held in with screws and bolts. Always disconnect the battery first. And each ECM is specific to year and model of your car. 1999 was the first year for CHIP key. Nissan immobilizer system needs to have the all of your keys introduced when the ECM is changed. Making sure the car is repaired properly so you don’t burn out the new ECM.