I looked at a number of youtube videos and it looks like replacing the O2 sensors requires specialized tools just for this task. Is it really that hard to get the old sensors off ? I don't want to give my money to a stealership or pay the going rate to a mechanic of $140/hr

They're known to be rusted on pretty well (and for some, practically brazed to the tailpipe), but that's the worst of it. My bolts were rusted up pretty bad and I was really worried about snapping or rounding them off, so I soaked them with PB for a couple days and they came off pretty easily. Otherwise it's very easy, all in all it should take maybe 30 minutes at most. Just make you sure you order the right ones, otherwise the plugs won't align (might not even reach) and it'll drive funky if you force it.. Trust me I believe I used the find-my-part on Denso's website for it
Go ahead and take a peek underneath your car and try to find them; you should have one before and after your catalytic converter, and really shouldn't be out of the way. If you have two cats, you have a Cali. emissions system, and should order the part accordingly. If I recall, cali T4Rs used an O2 and A/F sensor, whereas others used two O2 sensors - this is what screwed me initially, if I remember correctly, but I could have it wrong

By "PB" and A/F sensor I assume you mean, "Breaker penetrating oil" and "Air/fuel ratio sensor" ?

yes and yes

Unless you are on the ocean, a Mexico truck should not be that bad. Good to have a spare set of nuts. Stainless steel, M8-1.25. The studs are a lot tougher than the nuts, so if they are rusted, you can crush them with a vise-grip or pound on smaller and smaller cheapo sockets, whatever level of violence needed, if any. New nuts and clean the studs with a wire brush and away you go.

Some excellent ideas here.
I just bought the vehicle.
The T4R was licensed in California and I have no idea of it's history. But Southern Calif is quite dry and, of course never has snow, rain is a rarity.
You gave me an idea that I had forgotten. I could be wrong but isn't there a special tool that snaps nuts with a heavy, sharp edge that you keep torqueing on until the nut snaps in half ??

Why are you replacing these? Are you getting a CEL for them? Bad mpg? Have you gotten an OBD2 reader yet to see if and when your computer readiness monitors clear?
Have you been driving it in mixed traffic conditions and speeds to help set those monitors?

No I do not have a "check engine light". However, as you already know, California is a real *itch to pass the smog inspection. The T4R is running like a champ, 750-800 rpm when warmed up and in idle. No visible tailpipe emissions. My reading of the nightmare CA smog requirements would indicate that I could be labeled as a polluter, which might make future tests even more difficult.

What have I done so far? Changed oil and filter to 10w-40, new air filter, new platinum spark plugs, new PCV, cleaned the MAF with CRC MAF cleaner, new battery, radiator flush and new coolant, checked all vacuum lines for any leaks, added CRC "deep clean, guaranteed to pass" fuel treatment, and in the next few days I'll take it out on the hwy for 200 miles to , hopefully, clean the entire fuel system.

Am I being paranoid ? Maybe, but I don't trust those CA smog inspectors.

This is exactly how the 96 was. Two rust balls. Sharp jaw’d channel locks turned them to dust.

A nut breaker is what you are describing.

You may find you will have a harder time getting the connector to separate than actually removing the sensor.


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