Heres a question: Heated narrowband O2s ever need replacing?

Have a vehicle that seems to use two very expensive narrow band O2s. Ive taken other heated O2s out after 100k and they are very clean internally. No deposits at all. To me it seems as long as its not poisoned by any contaminates like antifreeze or silicone they should be good indefinatly. True or false?

 

False. Combustion is not a clean process. How long they will last will depend on may factors includin how clean the engine runs, how well the shield is designed and how sensitive the elements are. I've seen people running some into the 150K range... though I doubt I'd push it that far myself.

As a side example... the Gen III SHOs have a 100,000 mi replacement interval... I've yet to meet anyone that happily made it to 75K. The recommendation floating out there IIRC id 50-60K for those cars. I did mine at 40K. :shrug:

 

One of the engines with 120k I took one out of was running like puke. Still ran like puke after the new O2 but the old unit (actual zirconia coated ceramic probe) was spotlessly clean. The heating element seems to do a good job of driving all the garbage off. Although thats not to say that there arnt certain things that will still survive the heat treatment and cling to the surface.

 

Its funny how expensive these heated NBs are. Almost as much as the freakin WB. Im giving the fnord some lovin by doing a major tune-up and its gonna cost like 120 for the botch units.

 

My OBD-II Ford didn't cost that much for o2 sensors.

i agree with Red Devil. The heated part has a few goals. It helps lower emissions by allowing the o2 sensor to get up to operating temperature quicker, to allow them to start to provide feedback quicker. They also had a purpose to help prevent the o2 sensor from going back to "sleep" during idle conditions where the exhaust volume would be less, thus, it was common for non-heated o2 sensors to "sleep" during idle, causing the system to go back to open loop mode.

 

I had to replace one side on the wifes '94 Explorer...IIRC about 55 bucks at Kragen for a Bosch...assume you mean 120 for the pair?

 

Ive known and have had experience with that with the non-heated O2s. In the winter with headers the O2 just never warms up and causes wildly swinging AFRS as teh computer tries to get the desired output. At idle Ive gotten gradually creeping BLMs from the O2 cooling off.

One of the really nice side effects of the heating is that it seems to keep the O2 very clean. With my non-heated one, all the soot and crap in the exhaust settle out onto the sensor, which is probably the main reason the old O2s have to be replaced so much.

 

Bosch does have different replacement intervals for the different types of o2 sensors in use (heated,non-heated,OBD-II generation).

Not sure if you have access, but can you see the o2 sensors "switching" fairly rapidly? As o2 sensors age, their response time decreases. Normally, the o2 sensor should be reporting rapid "switching" back and forth in regard to mixture.

 

I cant scan this car unfortunatly... Wouldve provided a conclusive yes or no as to whether they neede to be replaced. I just went ahead and replaced them anyway.