trevdog

I See that the Denso has the flange/mounting plate on them. From the photo it looks like they are threaded into that, the plate could be removed and the sensor could be screwed into a threaded bung, which looks easier to weld into my exhaust. My donor truck didnt have any sensors and the one on my original 3.0 looks like it doesn't unscrew from the flange. Could be 300+K of rust, but I think it was originally one piece. If anyone can verify that the OEM Densos are "Threaded" that would be great.

Malcolm99

3rd Gen 02's are flange mount, I'm sure you can order the same 02's threaded but you might have a hard time deciphering the part #'s, and tapping or replacing the existing bung. Most replace the exhaust area that has broken threads on the 02 bung, you could also cut out that section from a doner and weld that in. It is not wise to weld the 02 on for a few obvious reasons but it does work,... sometimes. The OEM 02 threads are made of something like nickel, they are far superior to aftermarket stuff.

TheDurk

Most, not all. Rear O2 sensors in 2001 and 2002 are thread mounts, all the rest are flange including the Air/Fuel sensors used in front in later years.

There is no way to remove the flange from the flanged O2 sensors, but you could use the rear sensors from '01-'02.

Front and rear O2 (not A/F) flange sensors are interchangeable--all those p/n's are the same except for wire length. There is a Denso universal with just wires that replaces all of them.

Malcolm99

Thanks Durk again as always a wealth of knowledge!. My apologies, I had no idea they made that change, but in my defence the 01-02 are rare around these parts and an oddity of there own with the "updates/down grades" they received.

trevdog

Thanks for all the info. It seems like this would be a common issue for those doing the 3.4 swap and building their own exhaust. After hunting around I found what I think will work: Denso pn DN24154. Found some on ebay for $34 ea.

trevdog

Update on the O2 sensors I bought. I'm getting a P0141 code: the rear sensor. Truck runs fine, but the yellow light on the dash is annoying.
My donor truck was a '99 Tacoma MT. The dealer looked up the VIN and gave me a part number: 89465-09110. They also want $187 for the thing! They couldn't cross reference my Denso number of DN24154.
Neither the dealer PN or the Denso that I bought seem to match up to any of the numbers listed above. Seems I either got the wrong sensor on ebay (though it shows a vehicle match) or there is an issue in the wiring. ORS did the harness and I honestly wouldn't know where to begin trouble shooting.
Does anyone have suggestions for testing the wiring?

trevdog

I've been trouble shooting this damned PO141 code and I think it is due to a faulty ground on the O2 sensor heater cir. (volt meter shows nothing between the two black wires, but shows 12v between one of the black wires and the body ground) I'm wondering if I should just ground this wire?
I'm also wondering if the ECU somehow controls the O2 heater through this circuit, and grounding would result in the o2 heater running constantly.
I'd be grateful for any insights

TheDurk

Year? Model? On my 4Runner, 12V+ comes direct from the fuse, and grounding goes through the ECU. The power is cut off by the EFI relay, so it would not be continuous, but it would guarantee you have that code forever. I'm not sure if the ECU controls that grounding, or just monitors the current to it.

trevdog

Thank you. It's a '93 Pickup, engine swap from a '99 Tacoma. Both manual, non CA. Seems like the faulty ground could be somewhere in the pinning of my conversion harness. Maybe I'll give ORS a call and see if they have suggestions.
Am I correct that all the O2 sensor heater does is get the sensor up to temp quickly- for emissions sake? The truck seems to run fine, so if running a bit rich until the sensor heats up is the only drawback I see no sense in manually grounding that wire. I'll have the code either way.
If anyone knows of other performance issues that could result from this code please do speak up.