1999 GMC C1500 Oxygen Sensors

Tiny
JWMILLER
  • MEMBER
  • 1999 GMC C1500
  • V8
  • 2WD
  • AUTOMATIC
  • 90,000 MILES
I'm wondering if I can get away with only replacing the upstream or pre-cat sensors. My Suburban has 4, and is not experiencing any problems, except for lower fuel milage. I've read about the sensors and everything is telling me that the two upstream sensors are used to adjust fuel mixture, while the downstream ones measure the effectiveness of the Cat. Is it ok just to replace the upstream sensors? What problems might this cause?
Monday, October 13th, 2008 AT 1:36 PM

1 Reply

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi:
Yes you can replace only the upstream sensors, and it will not cause any trouble. Make sure, however, that they are bad. Have them tested prior to replacing by having the computer scanned for trouble codes. Most parts stores will do it for free.

Joe
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Monday, December 15th, 2008 AT 4:56 PM

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