That would depend on the size of the engine as well as if you are looking to replace the upstream sensor or downstream. Upstream simply means its in the exhaust system BEFORE the catalytic converter while downstream means that it is located after the converter. You need to have someone pull the DTC's, diagnostic trouble codes, from the ECM before you start replacing sensors. The code(s) you pull from that should point you in the right direction to which sensor is giving you a SES light or Check Engine light. I just recently pulled code P0420 on a 2000 Alero with the Quad4 engine. The code simply stated that the output on sensor 1 bank 1 was below threshold. I replaced the sensor and now everything is kosher. Some instances arent that lucky. Good luck with whatever you determine the cause is.
Dale
beside thermostat
the O2 Sensor Should be on top of your exhaust manifold
1st o2 senor is between exhaust. 2nd o2 sensor is under shifter
its mounted on the transaxle under the car
On a 1999 Oldsmobile Alero, the knock sensor is located on the engine block. It may be bolted to the intake manifold, or to either side of the block.
Go to AutoZone to borrow the tool and purchase a Bosch O2 sensor - the rep can identify the model number you need and show you on a diagram where the sensor is located under the car. The job is very easy and can be accomplished in an hour.
one of two things, the upper o2 sensor or the camshaft position sensor
it is right above the oill filter just to the left
Where is the charging port for the a/c in a Oldsmobile alero
brake light on when driving oldsmobile alero
a bad sensor. the alero is notorius for many bad sensors. not an expensive replacement though
They are in the exhaust flow