Downstream oxygen sensor, replace again!

2003 2.7 with 287K miles. I will be replacing the downstream oxygen sensor again due to the p0136 code. This is the third maybe fourth one, does this sound normal? I am on the second upstream oxygen sensor maybe I should just view it as a routine replacement part. I can reset the check engine light with my Scangauge. I routinely get 22 - 23 MPG. Drive like a grandpa.

BTW, I have been running 90 octane ethanol free fuel for about 8 months now. Get better gas mileage and engine feels a bit more responsive. Thank you Sheetz!

 

What brand sensors are you using when you replace them? Are you testing the sensors you replace to see if they are actually broken? It could be something else in the system that is causing them to fail. A rich condition, which dumps unburnt fuel into the exhaust, etc.. If you have a SCII maybe monitor the fuel trims and see where you're at.

 

I have read about burning coolant, definitely not my issue. Does not consume a drop and I routinely change it.

 

My last one was Bosch, I think. The one I just ordered is Denso. My Scangauage always shows 0 + - 1 short term fuel trim, long term does show + 6 or so. Don't quite understand how that could be though. I have not tested the sensor, but will this time. Do you know the parameters of a good sensor?

 

Well I would tend to agree but the way the truck runs including the gas mileage I get would tell me otherwise. I have cleaned the throttle body in the past, not sure where I would look to change lean the fuel mixture.

How long do Oxygen sensors last if all things are perfect from the engine perspective? I do have nearly 300K on my truck.

 

I wish I knew of a mechanic I could trust, simply I do not. For the price of these, $72.00 from Rock Auto and the life I get out of them at this point which seems to be about 80K miles I may just live with it. At least I know I can get the nuts free on the sensor since I am in there every few years!

 

Did my valve adjustment this summer, maybe 8K miles ago. Runs smooth as can be, no misfires. Only a few shims needed to be swapped. Did the work myself, not that difficult but indeed important on these engines.

 

you checked the connector?is it clean...pin fitment?

 

Found this with Google search -

And lastly, how long do oxygen sensors typically last? Older vehicles have O2 sensors that will typically last 30,000 to 50,000 miles, or 3 to 5 years.

I fall into that category, maybe I am just overthinking it?

 

Which connector are you referring?

 

It sounds like you have a pretty good idea of where the health of your motor is at. Really the only other major thing would be cats themselves, but if those are ok, then it's likely just miles or age that's getting them. I'm personally on my 2nd set of replacement sensors on my 3.4 @ 150k. They've been fine, but I think I am due for a smog this year, so they'll probably go out a week before I get the notice

 

the connector on the truck the 02 sensor plugs into

 

See how long the DENSO lasts...

My original DENSO sensor lasted close to 160k miles. Well known that our trucks don't play nice with aftermarket sensors. Stick with DENSO. Also, make sure you pulled the correct part# when you ordered. Check here. https://www.densoautoparts.com/

For your 2003 2.7, it should be --

AFR sensor:



O2 sensor:

 

Oh, got it. Certainly will when I have it apart to install the new one. Can't imagine an issue due to the location of the connector inside the cab.

 

Oh and if you order from Amazon, make sure it's "Sold and Shipped" by Amazon. Anything else and you run the risk of "who knows which cheap knock off" is in the package.

 

Yup, Rock Auto (

$61 234-4189 Oxygen Sensor

234-4189). $71.78 to my door. Beats all my local places by at least $30.00.

 

oof.

 

Rock Auto has been good for me. Good point about Amazon!

 

I suggest hitting the connectors with electronic safe contact cleaner no matter what they look like. Let them dry completely before you hook 'em up again.

 

Well, I guess you just found the one thing which hasn't been affected by inflation or supply chain issues