@circuitsmith - Just saw your post - what is the meaning of “pre-cat”? How long ago did u sell it?
Pre-cat means the sensors were located upstream of the catalytic converter.
One sensor for each pair of cylinders.
Sold it in 2008.
@circuitsmith - thanks for getting back to me.
Eight years ago, I did not have any issues with emission on my car.
Don’t u think parts can deteriorate exponentially?
@Barkydog
I found people are changing the upstream O2sensor to boost gas mileage.
On my OBDII Acura, upstream O2sensor is just under $30 whereas downstream O2sensor is $80 or more - both NGK brand
@sciconf Looks like the post did not go through, so if it is a repeat will modify later. Kind of torn, sure bosh o2 front and rear are 52 or 62 dollars, small bucks, but if no cel how to decide? no emission tests for efficiency evaluation, I would appreciate any wisdom on the suggestion.
@Barkydog - my car failed SMOG without a CEL - because, O2sensor was still doing something but not like a new one - its performance degraded over the years. The moment O2sensor was changed it was passing marginally. Bad O2sensor has also damaged the CAT over time. So a practical tip is to change the upstream O2sensor around 100k and when you are changing the Spark plugs.
@Barkydog - If you have the OBDII tool and an Android app, you may able detect O2sensor’s performance. I do not have the OBDII tool which cost me $30 - app software might cost me $5. But I can buy upstream O2sensor for $28 - so I am going to do this to my car which has $116k but it is 16 yrs old.
I was looking at one today, https://play.google.com/store/apps/details?id=org.prowl.torque&hl=en torque pro, did not see if I need to buy a bluetooth adapter somewhere. Learning, thanks
@sciconf mis read as scionf, but now think science conference?
@Barkydog - Also Honda owners had issues with Bosh. Therefore, I would only use NGK or NTK unless mechanic is finding the part. I just made the handle a while back.
There is Dash: http://lifehacker.com/how-to-unlock-a-treasure-trove-of-useful-data-from-your-1563366446
https://play.google.com/store/apps/details?id=com.dashlabs.dash.android
If you have an urge to change Spark plugs, you should have the same urge to change the upstream O2 sensor.
For my 2000 Acura, I found part # for the upstream O2 sensor on Amazon and bought it on jet.com for a discount. I feel the difference when I drive - as I press gas, I feel the “power continues to come” - I am enjoying it - with labor $60.