O2 sensor
 

Hello, My check engine light came on and I checked the code using the on board diagnostics. The code that came up as a 1221- O2 sensor. I bought a Bosch replacement one (with the correct plug) but the check engine light is still on and it throws the same code 1221. How do you turn the light off ? Do I need to buy a code scanner to do this ? Or will the on board system figure out that the O2 sensor is new and turn off the light?

Yes,
You will need to reset the check engine light yourself by using either a reset tool or as you mentioned scanner.

I'm not sure but it might clear itself. There a certain classes of codes that only leave the light on for 10-ish drive cycles then the light goes off. The code should remain in history but no light.

It sounds like yours is OBD-I. You may be able to clear all codes by disconnecting the battery and reseting everything by touching the battery cables together for 5 seconds.

Yes its a 1994 325i

Sweet , I unhooked the bat waited then touched both unhooked cables together and......----- vola it worked !

Thank You all so much

Cool,
I guess we both learned something new today - Thanks Jeron.

I'm glad it worked for you.

Be aware you wont pass inspection after a reset (any type of reset) until you have driven the car the minimum number of drive cycles. A week of daily driving should be plenty.

Ok ,I will keep that in mind. I don't need a inspection for smog until December of '08 so that should be plenty of time. Once again ... Thank You!!!