I threw a CEL for which I know is an o2 sensor...just not sure which one...I tried jump the wires to count the blinks but was unsucessful... which o2 sensors generally go bad first? TIA
The CEL also doesnt show from time to time when I start the car on certain days, but does more often thean not...?

bank 1 sensor 2 is usually the first to go. just replaced one on a 98. the part is 99 bucks, I paid someone 40 for the install.

if one is going bad.. you should just replace both.. try RockAuto.com they are pretty cheap.. also if it's the sensor in the front , you can change that yourself.. i mean it's just like unscrewing a light bolt.. but the one in the back.. now that's a pain in the butt... i try doing that. and let's just say thank god i don't ever have to do it again....

I disagree.......usually it's B1S1 that goes bad. The one in the back, by the firewall, up top. Just my 2c

But yes, you should replace both the upstream O2 sensors at the same time.

Yes I'm quite capable of changing both...I am still trying to figure out which one is bad, the one on the exhaust manifold or the one down by the cat...I'll probably just by both of them new, so there is a fresh matching pair. Any hints or suggestions as to where I can find OEM ones cheap? TIA

Doesn't Autozone check codes...for free? I have rarely changed a downstream O2 sensor (aft.cat) I suggest you replace both upstream sensors (in the exhaust manifold)
Note: B1S1 means, Bank 1 Sensor 1. Bank 1 is allways the side that cylinder #1 is on, in your case in the rear, by the firewal. Sensor 1 is the upstream/top sensor. Sensor 2 is downstream/bottom or after the cat.

Autozone says they can't check the codes, that they can only can 97 up ES's...so there are actually 3 o2's? The front and rear upper exhaust manifolds each have one? So the best bet is to replace both uppers and leave the one by the cat?

your 96ES is obdii compliant.. you have the diagnostic port in the fuse panel next to the driver's left knee. humor them and tell autozone your car is a 97+ model.. they won't know the difference in model years. better yet hold them by the hand and point to the diag port. they can scan your car. get the codes from them. i've scanned my 95es a few times already by autozone. for the record, my B1S1 went out few years ago.. other two sensors are still original.

The main o2 sensors go bad first from the crap that flows & burns through them (Gas).

All 1mz-fe's are OBD-II complient, but 94-95 have Toyota OBD-I connectors making them non-generic scanner (or OBD-II) readable.


'96's should be readable, depending on which part of the produciton run they were made in.