(I hope this is in the right section?)

Im going to try and break this up so its clear and short to the point:

Vehicle: 2004 Chevy Blazer ZR2 (4.3 V6)

Problem(s):

Truck threw code (P0155) - 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

To check to see if the 02 sensor was actually bad itself I swapped it for the one that was equivalent to it (in the Bank 1 sensor 1 location) in hopes it would throw another different code. It was quick and simple and if i didnt have to spend the 70 bucks on a new one i considered it a job well done.

It cycled and then eventually threw the code for the "in question" sensor in its new location.

The code was now: (PO135) - 02 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)

I bought a new one (Bosch I believe ) replaced it and recently it threw the code again (PO135)

Now incase this is confusing and could have anything to do with the trouble im having the original sensor from the passanger side was put into the drivers side and then later replaced. So now I have a new one in the drivers side position and an old one that hasnt caused any problems in the passanger side location.

Now this leaves me with a **** ton of options as to what is causing it to go off and if it has anything to do with the fact i swapped the old one to this location previously. Im not sure if its coincidental or not but everytime it throws this code it always happens either on a very cold morning and/or right after it was started previously on a cold *** morning.

Does anyone think it has any relation to it? My truck does take a while to warm up (thus allowing the idle to drop. It idles around 1k to 900 then drops to around 5 or 6) Itll take about 5 minutes or more.

Is the sensor i bought a piece of **** and could be bad already?

Is it just getting a bad reading? Possibly a bad or dirty MAF? I was thinking about taking a look at it and getting a can of cleaner. My truck has never been good on gas. Anyone have any input?

 

I think the sensor itself is in question, I am an idustrial maintenance Mechanic, and we go through our share of brand new Junk,, It happens, since you moved the sensor and the problem followed it, I would definately say that is whats causing your problem. I can tell you now that they will not exchange it, they wont work with people on electrical parts. First thing before you replace it is to check the connectors and make sure they are all in good shape, no loose or broken wires. However like I said the DTC followed the sensor, so theres a red flag.. Hope this helps

 

Im pretty sure I bought a junk sensor. Never going to get Bosch again. Im going to test it tomorrow. If it doesnt work im going to spring for another from either AC delco or Denso (stock ones are denso) and hammer the old one flat out of frustration.

 

One of the few things on a car you should always go OEM with IMO...o2 sensors.

 

Well I got under it today and ran a test to see if the plug was even putting out juice, which it was so that leaves me to suspect the sensor is a POS. Now I just have to find a place that sells a reputable brand... Either AC delco and Delphi or a Denso to match the rest of them. What a head-ache!

I didnt think a Bosch would be so terrible. Lesson learned and thank you for the help! Ill be putting a new one in soon.

 

I think GM sells Denso as oem now.