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1995 Land Cruiser O2 sensor mayhem?

Aaaagh!

So my mechanic says my 1995 Cruiser with 127k miles needs a new 02 sensor. This is the 2nd time in the last 6 months, and the first time I used a Bosch part and put it in myself but since the problem recurred, I figured just for protection/warranty I'd have my mechanic do it. So this time I buy the Toyota part; $200 parts and labor. Within 10 miles, the check engine light is back on. Back to the mechanic. His meter shows that the sensor is doing NOTHING, which is what it showed my 6-month-old sensor doing too... nothing. He said it would basically unheard of to get 2 bad 02 sensors like this and suspects the computer or an arcane problem of some sort. He was so surprised to have his meter showing 2 dead sensors like that, that he first suspected his meter was broken.

I love my mechanic; he's done tons of free work for me over the last

20 years, has passed on several chances to screw me royally, etc. He replaced a clutch for free when the first one he put in was defective. He has my trust. So, no worries about the shop- I love these guys. My worries are, what the heck might be happening?

My mechanic is researching the problem. He says he will probably try to borrow a used computer to put in there to see if that's the problem, if possible.

The vehicle is running perfectly. Any ideas?

-jeff

Reply to
Jeff
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The first step would be to check the resistance of the wiring and connectors from the O2 sensor to the computer.

Reply to
Mike

Do you mean that a scan tool showed no O2 sensor output? If that's true, then the scan tool should show the ECM trying to radically adjust fuel trim. The O2 sensor output is what the ECM uses to do that. Is the O2 sensor heater working? The scan tool should show that too. A bad O2 sensor heater circuit would cause faulty O2 sensor operation particularly during warm-up and maybe when idling too. Good luck. Al

Reply to
al

Here's how it was explained to me... the computer is throwing a check engine light, and the codes point at the #1 02 sensor. When my guy put his "meter" (not sure what he means by that, but it's a full- service mechanic shop that's been in business for decades so presumably they have all the stuff) on my 4-month old Bosch 02 sensor, that I'd installed myself when something similar happened a few months ago, it showed the sensor was dead- not doing anything. So I sprung for the Toyota part and had HIM install it this time. Within a very short time the CE light came back on. Codes show bad #1 sensor, his meter (and now his co-worker's meter, just to be sure) show it to be dead, not doing anything.

He says that's not really possible and that maybe the computer is somehow suppressing or interfering with what he's reading. Or something else is going on. He's researching things on his end. He's not charging me for any of this, and this isn't a rip on my mechanic- I love the guy. I just want the CE light to stay off and to stop buying 02 sensors!

-jeff

Reply to
Jeff

Take this over to the Toyota board and ask Ray O. There is a procedure to test the sensor independent from the computer. I think you have another bad sensor.

Reply to
Jeff Strickland

What's the Toyota board?

-jeff

Reply to
Jeff

Sorry, alt.autos.toyota.

I thought I've seen you over there already. I get confused easy ...

Reply to
Jeff Strickland

Oh, I've been over there a few times over the years... maybe you aren't so confused! :-)

I think of these as "groups" but I know boards is a valid way to describe them too. Old school! Usenet.

-jeff

Reply to
Jeff

Board, group. Potato, potahto.

Ray can describe a way to test an O2 Sensor. I've not followed the procedure, so I do not want to repeat it for you. Normally, I do not buy into the theory that the sensor needs to be tested, I just replace them when the computer tells me to and I've had good luck with that. I understand why testing is useful, but in my case I've had original sensors in that were there for going on 10 years, and I like the odds that say they should be toast by now. Your sensor is relatively new and ought not be toast yet, so I'd certainly test it before buying a new one. I'd have to ask Ray to 'splain me the procedure though. It's really easy, I simply don't know what the results ought to be at various stages.

Reply to
Jeff Strickland

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