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Where is the oxygen sensor/oxygen sensor harness located?

Tiny
LEVELTWO
  • MEMBER
  • 2004 FORD F-250
  • 5.4L
  • V8
  • 4WD
  • AUTOMATIC
  • 208,000 MILES
I can't locate the downstream sensor harness wire under truck.
Saturday, December 9th, 2023 AT 2:22 PM

10 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,724 POSTS
Hi,

Was it connected before working on the vehicle? Also, on some sensors, the wiring is connected to it from the factory and the connector is in the engine compartment.

Let me know.

Joe
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Saturday, December 9th, 2023 AT 11:00 PM
Tiny
LEVELTWO
  • MEMBER
  • 6 POSTS
It seems as if there was no downstream oxygen sensor, or downstream harness wire.
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Monday, December 11th, 2023 AT 12:43 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,724 POSTS
Hi,

Check behind the engine to see if anything is disconnected. I'm not sure what someone has done. The wiring from the sensor goes in different directions, so there has to be a connector at some point.

I attached a pic below at least showing the wire colors you should be looking for at a connector. It should be a round connector with 4 pins.

Let me know.

Joe

See pic below.
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Monday, December 11th, 2023 AT 8:32 PM
Tiny
LEVELTWO
  • MEMBER
  • 6 POSTS
Thank you, if I`m getting it right, if I don`t have a California truck, I won't have a down flow oxygen sensor.
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Wednesday, December 13th, 2023 AT 2:57 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,724 POSTS
Hi,

According to the wiring schematic, that appears to be correct. Is there a place for one in the exhaust or any indication one was present?

Joe
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Wednesday, December 13th, 2023 AT 7:08 PM
Tiny
LEVELTWO
  • MEMBER
  • 6 POSTS
Originals exhaust, no place present for downhill oxygen sensor, no wiring harness visible.
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Thursday, December 14th, 2023 AT 12:45 AM
Tiny
LEVELTWO
  • MEMBER
  • 6 POSTS
  • 2004 FORD F-250
  • 5.4L
  • V8
  • 4WD
  • AUTOMATIC
  • 108,000 MILES
Exhaust systems look as if it's original there's no place for the downstream oxygen sensor nor is there a harness for the downstream present.
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Thursday, December 14th, 2023 AT 12:55 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,536 POSTS
There is only the downstream oxygen sensor on California trucks. Let us know if you need anything else.
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Thursday, December 14th, 2023 AT 12:55 PM (Merged)
Tiny
LEVELTWO
  • MEMBER
  • 6 POSTS
Thanks.
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Thursday, December 14th, 2023 AT 12:55 PM (Merged)
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,536 POSTS
You are welcome, please use 2CarPros anytime we are here to help.
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Thursday, December 14th, 2023 AT 12:55 PM (Merged)

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