I went and failed my emissions test becuase of the following code:

P0141: O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)

The truck runs good and gets great gas mileage, but I need to pass emissions.

Do I need to replace an oxygen sensor or is it something else? If it is an o2 sensor, what one is bank 1 sensor 2?

It is for the truck in my signature.

Thanks so much!

 

It should be the O2 sensor ahead of the catylitic converter for your year...check the connections and wires to the sensor...if you have a volt meter make sure that all the wires are good...

Here are the locations for your year truck (97 4x4).
[IMG]local://upfiles/1127/39A71B376C554CE68D2093E77978D38A.gif[/IMG]

[ol][*]Remove the electrical connector by releasing the locking tab.[*]Carefully back out the heated oxygen sensor you are replacing. [/ol]
[ul][*]HO2S Bank 2 Sensor 1 (1)[*]Catalytic Converter (2)[*]HO2S Bank 1 Sensor 3 (3)[*]HO2S Bank 1 Sensor 2 (4)[*]HO2S Bank 1 Sensor 1 (5) [/ul]

 

B1S2 is the pre-cat O2 sensor (directly ahead of the catalytic converter). This sensor and the next one further back have no impact on the fuel delivery of the engine so that would explain why you are getting good mileage.

More often than not, this is a faulty sensor. What to do first would be to check the wiring harness and make sure that there are no rips/tears/bear-spots in the harness and that the connector is clean and fully seated. If you need to clean the connector, you will need to make sure that it is dry before reconnecting it.

Once you have checked everything over, reset the PCM either by having Advanced Auto or Autozone do it, or by disconnecting the battery for 15-20 minutes. You will then need to complete a 'drive cycle' before you can go in for inspection again.

If the code comes back, then I would recommend that you switch the sensors from in front of the cat to behind the cat. If the code follows the sensor, then it is indeed bad. If not, then there are problems elsewhere and that can get interesting.

Hopefully you have some time to work this through...

As always, I only recommend AC Delco sensors. This is after seeing many of the top brands side by side in the same vehicle, watching their cross counts (activity) and trace (actual response). AC Delco sensors are by far the most active. NGK sensors (if you can find them) are a very close 2nd, but the main stream Bosch and Borg Warner sensors were by far the worst that I experimented with. And always get direct plug in sensors, no universal sensor.

 

Thank you so much for the help! We have a code scanner at work that I borrowed so I am able to read and clear codes.

It looks like an easy fix.... or so I hope.

As my signature says... I put 200 miles a day on the Blazer so it takes a pounding.

Thanks again!

 

wow i thought sensor 2 was on the passenger side down pipe is the pic 20blazer00 posted correct? whats up with #2 it looks like it is pointing directly to the cat? i have the same year i have replaced 2 of my 4 o2 sensors and i had codes just the same, it fiexd the problem but i apprently replaced the wrong one!?! how would this still fix the cel?

 

Yeah it should be correct I got it from a GM Service DVD that I bought on E-bay.

And # is pointing to the cat read after the pic and note that #2 is listed as the Cat...

 

i get it now sorry brain lapse