Hey, I know you work with a shop on bimmers, so I wanted to throw this question by you to see if you know. I just had a CE light come on, so I pulled a code by doing the floor it 5 times drill, and i'm getting a bad o2 sensor #1. the code number is a 1221. Do you happen to know which sensor is #1??
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325iNV is correct. The rear o2 sensor are usually on cars model years 1995 and on.They are normally found on cars that are OBDII REQUIRED.That is a California Emission Standard.Based on engine size and engine year.
All o2 sensors are located only in the exhaust system.The o2 sensor in front of the Cat. Converter is for fuel management. It is used by the PCM ( engine computer) to determine fuel pulse width ( injector on time).
The o2 sensor generates a higher voltage in the absense of oxygen .About .9 volts D/C when the exhaust is rich.And a lean exhaust is about .02 volts.
A good running engine at idle should show a voltage varying from .4 to .7 volts.
The o2 sensor after the Cat Converter is used to monitor Cat converter efficiency.
Both sensor can be test with a Digital Volt Meter only.You can not use a analog volt-meter.
Desmobob says that you have obd1 which would mean that you have two o2 sensors.
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