Engine light

I replaced my factory am/fm radio on a 1997 altima and noticed after I had taken it out that my engine light had come on. The light was not there when I started the swap. Is there some type of anti theft device that could of set this off? Is there any way to get it to go off?

I have taken my altima in to get checked for a engine light and they said it was cause by port 3 being faulty. They changed the plug and reset the code. It went again and they said it was a fault on port three again. They fixed it a second time and claimed it was caused by injector plugged. Three days later my engine light has come on again and the car is sucking gas big time again. Anyone out there had this type of problem and what was the fix.

I have a similar problem. I had the engine light on and it was a code p0420 which read Catalyst below threshold. I had the code reset and did a small tune up. Plugs, air filter and premium fuel. The code has not come back on but the FUEL WASTE is rediculous. The dealer says I need to wait till the code comes back on in order to fix it. If you get any info pass along the car is parked for now since it was a commuter car but at $23 for 250 miles it is not worth it since that is only a day and a half of commute.

I have a 95 Alti and my check engine light has been on and off for the past 3 years. I took it to a mechanic and they couldn't find any problems with the engine. My car runs great, only hypothesis is that my exhaust is causing some kind of sensor error.

I have had my car in to get the engine light fixed many times. They keep saying it was a plugged injector or they forgot to reset it. At any rate I am getting around 500 km for a tank of gas. Not great when I pay 35.00 to fill it up. I plan on selling this car and going back to something dependable ( not a Nissan). I have found too many people who have had problems and never get them fixed by the dealers cause they cant fix them