How is it possible to lose all O2 sensors at one time? (1 Viewer)

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Mar 9, 2017
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Location
Mobile, Alabama USA
I have been trying to diagnose my problem with my 2001 LX 470 - 109,000 miles, since my local Toyota dealership can't replicate the problem in their service bay. 99% of the time my LX runs perfect and then all of a sudden while accelerating from a red light it will stall or start missing bad. It normally starts running fine after letting it sit for a few minutes.

"Luckily" the other night it when I was close to a handheld OB2 scanner. These first 3 pictures are of when it was missing very badly.

The other 3 pictures are when it is running perfect! The biggest difference I can tell from the pictures is that the LX 470 might be losing all of its O2 sensors at one time?

Please advise before I shoot this SUV and leave it for dead!

Btw since I was planning on keeping this LX 470 forever, in my past 6 months of ownership I have had my Toyota dealership do the following to get a baseline: new fuel cap, new air filter, new fuel filter, new timing belt, the MAF has been clean, clean throttle body, the Injectors have been clean, new spark plugs, new water pump, new belts, new alternator, radiator flushed, transmission flushed, differentials flushed and oil changed.

Lexus LX 470 #1 Running Bad.jpg


Lexus LX 470 #2 Running Bad.jpg


Lexus LX 470 #3 Running Bad.jpg
 
This is the same code reader. This is when the LX 470 is running fine which is 99% of the time. It only stalls every so often but, with no warning.

Lexus LX 470 #1.jpg


Lexus LX 470 #2.jpg


Lexus LX 470 #3.jpg
 
I would disconnect the battery, which forces a reset on the computer. See if it returns... Also, how old is the battery? A weak battery causes all kinds of headaches, and is a cheap fix.
 
I would disconnect the battery, which forces a reset on the computer. See if it returns... Also, how old is the battery? A weak battery causes all kinds of headaches, and is a cheap fix.

Thanks for the suggestion. The battery is only 3 months old and I have already tried to reset the computer but, the problem comes back.
 
I would treat the 02 sensor issue as a red herring, I would doubt your scanner first. I am not saying a 02 sensor isn't at fault, but for all to read 0v without a CEL then I would take it with a pinch of salt. Check your wiring harness for signs of damage though, and check your battery connections.
 
Another thing that is strange, is that all of your fuel trims are out, and they are all out by the same amount, so I would look at fuel pressure/fuel filter, MAF sensor, fuel condition, air filter and coolant temp/sensor as these would affect both banks the same and all cylinders.
 
Do you know anyone with Techstream to confirm the readings, I am just doubting these readings myself.
No sir. I am thinking about taking it to another dealership in the next town over so they can get a crack at it. I am tired of this moody LX!
 
No sir. I am thinking about taking it to another dealership in the next town over so they can get a crack at it. I am tired of this moody LX!

It might be for the best as If I was getting these readings on techstream then I would be worried about the ECM being at fault, as under fault, your coolant temp is good, your MAF reading is ok. Can't speak for fuel pressure so this could be a issue, but if you haven't got the kit to test then what can you do, but you still wouldn't expect 0v on the 02's.
 
Last night to try to guess at my problem, I swapped out my fuses under the hood and with DeoxIT gold contact cleaner.

The fuse on the right was my worse looking fuse and the fuse on the left is brand new. It was my Alt-S fuse that mounts to the battery. Do you think this fuse looks normal?

IMG_4257.jpg
 
Maybe this picture is clearer?

IMG_4258.jpg
 
Whats wrong with the fuse on the right? Looks like a 7.5amp fuse from the color.
 
I don't know of anything wrong with it. But it did have some discoloration on the metal prongs and I changed it just in case it had built up any resistance.
 
Check to make sure your MAF is plugged in and seated correctly.
Since they cleaned it and replaced the air filter double check their work, they don't use their top techs for that kind of work, they use newbies and apprentices.
 
Thank you Spike, I will try that
 

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