The following codes are causing Service light to display:
P0133 & P0135: B1S1
P0141: B1S2

I have a 97 Blazer, 4-door, 4.3L. I bought a Haynes book recently to try and do the simple diagnostics with a multi-meter. I have only been able to determine volts on engine side of connector:
B1S1 (which I believe is under the driver's floorboard) has 11.55 volts.
B1S2 (which I believe is just before the catalytic converter) has 11.23 volts.

It is my understanding that these readings should be at or above 12 volts. Is this a problem?

Also, which wires do I need to test on the sensor side for ohms? I think the Haynes book stated to test the signal (+) and the gound (-) but when I did, the ohms reading was not holding steady.

Thanks,

 

https://blazerforum.com/forum/2nd-ge...p-52028/page3/ All of them except b1s2 are bank 1, drivers side first one. Look at the 3rd post down with the link. Myself., I would change the first and see what happens

 

Is this truck new to you, what I mean to say is did it all happen at one time or you just don't know. O2 codes are most often set by the speed that they switch. As they get older they switch slower and that's what makes your pcm toss a code.


You really cant tell that much from a DVM. It needs to be looked at with a real time code reader, this of coarse if there is not some catastrophic wiring problem.

 

I have had the Blazer for about 3 yrs. I changed the sensor after the catalytic converter about 2 yrs ago. Problem is, the more I think about it, I think I told the people at NAPA that it was the one just before the catalytic converter, so I am not sure that I have the correct sensor after the catalytic converter.

I have had these codes for several months. The Blazer runs fine and I have been monitoring the mpg with it ranging from 18 to 21 in town and on the interstate respectfully.

 

I believe all the o2 sensors are the same

 

Autozone list Oxygen Sensors for up-stream and down-stream, before and after catalytic converter.