Mysterious missing O2 sensors

2001 FORD F-250
198 MILES • 7.0L • V10 • 4WD • AUTOMATIC
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APESGARAGEF250
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So is there any ideas on why my truck would only have two O2 sensors that I can find? I can't even find the place for the other two (the down stream) that should be in the area between the two doors.
Only thing back there is the fuel tank and the lights that I put in for my bed and all that is on the other side. TIA for all the help again guys!! Oh, and FYI, my mom ended up getting new van so the other question of mine from before is on the back burner for now, not so much a pressing matter.
Aug 21, 2021 at 9:15 PM
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SQM
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Hello,

First of thank you for using 2CarPros. We are always happy to assist.

That is strange that you are missing the down stream sensors.
Now does this truck have after market exhaust ? Maybe when it was changed the oxygen sensors were bypassed for whatever reason.

Usually when the sensor is mission the engine light will be illuminated. Is the engine light on?

https://www.2carpros.com/articles/how-an-oxygen-sensor-works

Let me know what you got.

Thank you.
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Aug 21, 2021 at 9:32 PM
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APESGARAGEF250
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Yes it did. now it's just straight pipes at the moment. but before I removed all of the exhaust it only had the two up stream and no cats and a flow master.
Aug 21, 2021 at 10:04 PM
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SQM
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So the previous owner might have changed it out before you.
Is the check engine light on?
Aug 22, 2021 at 9:06 AM
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APESGARAGEF250
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Yes, it read system lean on bank 1 and 2. The previous owner doesn't have a clue what was or wasn't done to it to be honest! So I'm pretty much winging it really!
Aug 24, 2021 at 12:45 AM
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SQM
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You can install O2 sensor adapter in to the exhaust if you wanted to have the sensors. However you first have to make sure that the wiring connector still exists on the truck that you are able to just plug in when you get the adapter.
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Aug 24, 2021 at 6:53 AM