Where is the O2 sensor located m 1 sensor 1?

Well it's not quite that cut & dried! .. Code doesn't indicate what part has failed .. What if it's a 'broken wire' going to the sensor instead? .. Maybe the exhaust gases are askew due to another system malfunctioning... Testing is required! .. (Bank 1 sensor 1 is in front of catalytic converter > bank 1 is nearest firewall.)