Radio code does not come up on screen

Depending on the make you can go online, search the make/model/serial number on specialist website that will sell you the code for a couple of bucks. As you didn't provide this in your question I couldn't test run it for you. Serial number may be in the drivers book or remove radio and it will be on the back. Has nobody written it in the owners books anywhere? Next time hook up a small motorcycle battery to your main batt leads before you remove the main batt and this will keep the codes in place while you swap the main batt.

Radio is usually wired as an accessories fuse on the panel. Is it possible there is power but you need to re enter the security code?
If you don't have the paperwork you may be able to get the code from an online site when you enter the make model serial number. It might cost a couple of bucks? Next time you disconnect the battery, make up a couple of leads with croc clips on, wire them to a small 12v battery and connect them to your batt leads before removing the main batt and the small battery will have enough power to keep your radio/ alarm etc working when the main batt is removed.

If the radio is a factory fitted unit you will have to supply the vin number of the car along with proof of ownership to the vehicle dealer and they will have it on record. If it is an after market unit then may a radio techi will be able to help. If you have the owners hand book it may be written in there or in the warranty section

short of buying a repair manual for the vehicle, id find someone handy with a multimeter and check to see if theres any voltage comin thru the wire when the key is on. it might be the power wire. the pfft sound you hear might be from where there is a batt. wire goin to the radio so you dont lose your programmed stations

you can get radio unlock codes here http://www.radio-code.com/

hi your code is 7278 hope this helps

You need to have the code read to tell you exactly where the problem is. Also you need to disconnect the batt for about 30 minutes to allow the computer to reset. And last but not least are you sure you replaced the proper O2 sensor, there are 2, one on the header and one behind the exhaust.

You can pull the radio and get the codes or call the dealer and get them up to you. You will need your vin # in the window and you will have ti have your name on the registration number before they will give it to you.

On the controls on the steering wheel hold the vol + & - for a couple of seconds and this should bring up the 0000 on screen and then its a case of spinning the wheel control on the side and holding + & - to set it.

Take the batts cable off an hold them together for 10 sec an that reset the compute your radio will read enter code