Getting P0172 & P0175

[JamesLond]

My B2S2 seems to be working since the voltage is changing, but the B1S2 isn't fluctuating at all and sticks at 0.445V. I also notice the short term fuel trims for both sensors are at 99.2%.

Is this high fuel trim normal? I think I'm going to replace the B1S2 as a first step since I followed the steps in the video to test wiring and wiring tested out ok.

I checked continuity on pin C & D of the O2 sensors themselves and I measured OL on B1S2 and 4.2ohm on B2S2.

 

[Fless]

Ignore the 99% fuel trim for all downstream sensors. They don't contribute to fuel trims so that 99% value means not applicable. Many scanners will display N/A for those PID values.

You could swap those sensors side to side to see if the voltage problem follows (meaning that O2 sensor is dead). Are you sure the heater circuit is working on the passenger side? Will it light a test bulb that pulls a few amps? He tests only for continuity, not the ability to carry the load. Although it's probably not the circuit or you'd get the heater code.

 

[rockola1971]

Yup. S2's do absolutely nothing other than to tell the PCM to throw a code that the catalytic converters are bad. The downstream (S2's) O2 sensors are not used for inputs for the PCM to adjust fuel injection.

When OL is seen on a multimeter when checking continuity that means there is not any continuity between the terminals that you are checking and C & D terminals of the O2 sensor is the internal heating element of the sensor. This explains why its not giving a good value to the PCM. You arent getting the preheat function to happen which is what the heating element in the sensor does. This allows you to go in to closed loop alot faster instead of the waiting for the exhaust to warm the sensor up. B1S2 is a bad o2 sensor.

 

[MassHoe04]

If the B1S2 (the one that still works) is original, save some headaches and change both down streams with a matched pair. They will have no impact on performance or safety, but will save you the constant codes.

I used NTK sensors on my 04. No issues since installed in October 2021.

If upstreams are happy, I wouldn't mess with those until one fails.

 

[JamesLond]

If the B1S2 (the one that still works) is original, save some headaches and change both down streams with a matched pair. They will have no impact on performance or safety, but will save you the constant codes.

I used NTK sensors on my 04. No issues since installed in October 2021.

If upstreams are happy, I wouldn't mess with those until one fails.

I decided to get the ACDelco 19355306 one.

After a little more searching I found a Denso one that's like $12 less.I'm kinda debating getting this one since it seems Denso sensors seem well liked.

Not only that, I might just put off replacing it altogether. Since they have no effect on fuel trims, it's not really going to help solve the problem at hand.

 

[MassHoe04]

I decided to get the ACDelco 19355306 one.

After a little more searching I found a Denso one that's like $12 less.I'm kinda debating getting this one since it seems Denso sensors seem well liked.

Not only that, I might just put off replacing it altogether. Since they have no effect on fuel trims, it's not really going to help solve the problem at hand.

If the code is intermittent and keeps coming in, that can just get annoying.
Having to check if this is a new code or if it is the one I am trying to ignore on purpose.

If the code you get is a constant one and the light is always on, you might not know if/when a new code is tripped.