P0147

O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 3)
96 blazer 4.3 w vin
This vehicle has the 4 sensors. which 1 is this sensor be
1 drivers side
1passanger
1 infront of cat
1 behind cat
1 infront of muffler (my guess is its this one?)
but been wrong before was married once

Thanks in advance
Greg

 

B1S3 is the post-cat sensor. The one directly behind the catalytic converter.

Here's an illustration:
[IMG]local://upfiles/667/75B2A32618CF46AC9B4FBAFEAC810D6F.gif[/IMG]

On the Blazer, B1S1 is on the driver's side of the 'y' pipe and B2S1 is directly ahead of the 'y' in the 'y' pipe on the passenger side. B1S2 is the pre-cat sensor ahead of the catalytic converter and B1S3 is the post cat sensor.

The B1S1 & B2S1 sensors are used for fuel delivery while the B1S2 & B1S3 sensors are only for catalyst monitoring.

You may want to check your wiring harness for wire damage just to be sure.