O2 sensor programming?

[blondie70]

I installed 2 upstream Denso sensors...no mention of programming.....but....after about an 80 mile run, I am getting a CEL. Code is P0171. My cheapo tool says "fuel trim lean".
I just ordered 2 GM OEM sensors. A note on them says some programming is needed upon installation. What programming ? Can I do it under my shade tree ? Thanks for any clarification...and heck...maybe the Densos just needed programming too ???

 

[strutaeng]

No programming required.

Bank 1 Lean? I would check for vacuum leaks on the bank?

What prompted you to replace the oxygen sensors BTW?

Edit: I see this is GMT900... maybe they are talking about resetting the fuel trims? IDK

 

[blondie70]

Thank you. Replacing due to 198K miles. Nothing was wrong until I replaced. I'm thinking it's the Densos. Got from Rock Auto and think I bought the right ones.....anyway..I ordered some others and they were much more $$$$ OEM. I reckon I will find out when I get 'em on there !!!

 

[Fless]

You could also swap the Denso sensors side to side and see if the code moves to the other side.

I'd probably document some short term fuel trims now, after swapping sides (if you do), and after installing the OE sensors. A decent scanner will also graph the O2 sensor activity.

 

[blondie70]

Well....I got code P0171 and my scanner said "fuel trim lean" ...don't think it pointed to a side. I am not up to ***** on scanners...ha. I do not have a fancy one. It's out in the shed, so I don't have the name and model to mention. I will try to graph sensors tomorrow and see what it sez. Thanks for the info !

 

[Fless]

P0171 is for the left bank (Bank 1); there is a different code for Bank 2.

It can be a bit difficult but if your scanner doesn't graph, you should be able to watch the voltage fluctuate on the upstream sensors. They should oscillate from 0.1 to 0.9v. If the voltage is consistently somewhat below 0.450v then that indicates lean.

Reading O2 sensor voltage ranges in Live Data

The voltage output of an oxygen (O2) sensor in a properly functioning vehicle can vary depending on the specific engine and the operating conditions.

www.innova.com

 

[j91z28d1]

I think it will probably go away with the oem o2 sensors.

I've never seen anything hate aftermarket o2 sensors like these.


the programing has to do with the heater circuit. I've not seen anything on these Gen trucks, but some cars will have a way to calibrat for the heater. back in the day it was just 12v power to the sensor. at some point it became a duty cycle that could adjust the temp. when or why programing become a thing I'm not sure but I've seen reference to before. again I don't believe we need it here.



hopefully the new o2 fix your code.

 

[swathdiver]

I've said it before and I'll say it again, aftermarket sensors do not play nice with the computers on these trucks. Especially O2 sensors. This even includes Denso sensors that are NOT in a GM/ACDelco wrapper.

There is a HO2S heater resistance learn reset that can be done. I didn't even know about this until recently and my new sensors have 32K miles on them now.

 

[Doubeleive]

I've said it before and I'll say it again, aftermarket sensors do not play nice with the computers on these trucks. Especially O2 sensors. This even includes Denso sensors that are NOT in a GM/ACDelco wrapper.

There is a HO2S heater resistance learn reset that can be done. I didn't even know about this until recently and my new sensors have 32K miles on them now.

did you find this on the tech2?

 

[j91z28d1]

Operation
HO2 sensor is supplied 450mv reference from PCM.
For proper operation, HO2 sensor should be over 600°F.
HO2 sensor generates a voltage dependent on the amount of oxygen present in exhaust.
Rich exhaust results in high HO2 voltage (above 450mv), lean exhaust results in low HO2 voltage
(below 450mv)
IGN(+) is supplied to heater which is built into HO2 sensor.
When replacing the HO2, sensor perform the following:
Clear codes with a scan tool, regardless of whether or not a DTC is set. This causes PCM to perform a
HO2S heater resistance learn reset.




huh. learn something new everyday.