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Thread: WBO2 sensor cleaning.

  1. #1

    Default WBO2 sensor cleaning.

    I've read where a Sniper WBO2 sensor is a "wear item". Really? Most cars get over 100,000 miles easy from WBO2s, but Sniper systems have a lot of issues with WBO2s. Why? Let's say for this discussion that the sensor is mounted at an angle, placed properly and no exhaust leaks ahead of it. Is there an approved way to clean a WBO2 sensor? Online reading & videos say soak in gas overnight, clean with tooth brush blow dry. Or the same procedure with carb cleaner, Sea Foam, starting fluid, lacquer thinner, etc. Or simply heating it red hot with a propane torch and letting it cool down. Has anyone here brought back a dead or failing WBO2 sensor? A $105 a pop is crazy. I already had to replace one due to being stuck at 35.6 AFR. Could it just be dirty? What are your opinions & experiences? Thanks, Danford1

  2. #2
    Join Date
    Dec 2009


    Please show us a picture of the WBO2 sensor installation. Is the failed WBO2 sensor fluid contaminated?
    When WBO2 sensors fail, they typically display a lean AFR. Cleaning the WBO2 sensor never seems to work well.
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  3. #3


    It's located in the exhaust pipe about 7" past the ball & socket connection on the header. About 12" back from where the 4 pipes merge on the collector. Notice the headers have an WBO2 port in the collector, but that's almost horizontal. I added the other one. Since I replaced the WBO2, I also added an O2 extender to help save the new sensor. I talked to Holley tech on the phone and he also asked about the placement. He then said it was in a good location where it is. What happens physically to the sensor to cause it to read 35.6? I guess I have to read up on the science of a WBO2 sensor and figure out how it works. The 35.6 sensor just looks black, what does fluid contamination look like? Danford1
    Click image for larger version. 

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    Last edited by danford1; 02-21-2019 at 06:25 PM.

  4. #4


    I just got the A/F Ratio of 35.6 and found out it's the WBO2 sensor. For anyone else that comes across this thread because of their WBO2 sensor, I got one from for $60 and it's the same Bosch sensor, but just not labeled as a Holley. They're good guys to get your EFI stuff from.

  5. #5


    I think I'm having the same issue. Started my truck on a 39°F cold day (first time ever in that cold) and my dad said he saw smoke from the exhaust quite a bit. Well anyways I had the 35.6:1 AFR, plugs were wet & fouled. Bought new ones and replaced them, and it still does the same thing. Max lean and smoking a bit. I hear stories of people having to send their ECUs back. I had mine maybe for a year and only 500 miles on it. Second set of plugs. I'm hoping I can reset the Learn Table and try a different sensor. 😬

  6. #6


    I'm having the same issue, my sensor is almost straight up on the pipe, no liquid fouling at all. My Sniper ran great for over two years and then started having intermittent issues. They progressed until I was dead lean all the time. I swapped the WBO2 sensor and it did the same thing. I'm waiting on the service ticket from Holley.
    But back to your original question. I took my original WBO2 sensor and sprayed it with brake cleaner. Then installed it with a different Sniper (my buddies that stopped sending a spark signal) and the car has been running very well for a couple months. YMMV

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