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2004 Toyota 4Runner O2 sensors codes

Tiny
AUSTIN SUNSHINE
  • MEMBER
  • 2004 TOYOTA 4RUNNER
  • 3.5L
  • 6 CYL
  • 4WD
  • AUTOMATIC
Good day colleagues, I have a trouble with a car that refuses to go permanently.. Po420. Po421. Changed o2 sensors, checked for air/ exhaust leakage, catalyst but the code comes on after a while with the Trac and vac light. Tanx
Wednesday, August 20th, 2014 AT 5:28 PM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,269 POSTS
I have to be honest, most times the converter is the problem. Did you check for vacuum leaks on the engine? Is the any black smoke from the exhaust that would indicate an issue with fuel pressure or an injector?
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Wednesday, August 20th, 2014 AT 6:02 PM
Tiny
AUSTIN SUNSHINE
  • MEMBER
  • 3 POSTS
Tanx.. I checked for leakage and found non. I dissembled the exhaust system to visual check the catalyst, they still ok. The exhaust pipe is not black but somehow pale without smug.. To my understanding the car does not consume fuel.. But has very minor engine missing.. The check light comes with the Trac/ vsc light. Pls advice.
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Thursday, August 21st, 2014 AT 12:49 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,269 POSTS
A misfire could cause this issue but forcing unburned fuel into the converter. Also, vacuum leaks can cause the misfire.
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Thursday, August 21st, 2014 AT 4:48 PM

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