BMW 525i Sevice Engine Soon

Hi, I just bough a BMW 525i and drive it home. The next day, I start the car up the Sevice Engine Soon came on. I buy a BMW Scan tool and check the code and it give me a code #19 is oxgen sener on #1-3 fell. So, I order a new oxgen sener and take the old one out and put the new one in. Then, I rest the Sevice Engine Soon light and start up my car and warming the car up for about 20minute and turn off the car. Then, I re-scan and get the code -- it meaning my car have no error. I think that I find the problem. If any one out there have the same problem on their BMW please email me. I can help. [email protected]