1994 Toyota Pickup Trouble code 27 and now 21 and 27

Tiny
COISC29
  • MEMBER
  • 1994 TOYOTA PICKUP
1994 Toyota Pickup 4 cyl Manual 225, 00 miles

Check engine light on trouble code 27, replaced front o2 sensor, rear was replaced about 5 years ago, after replacing front sensor I now have 2 codes, 21 and 27; 21 = main oxygen sensor fault, 27 = sub- oxygen sensor signal or heater circuit fault. Would replacing rear sensor fix the problem ? Or do I need to do something else?
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Monday, September 6th, 2010 AT 12:53 PM

5 Replies

Tiny
DOCFIXIT
  • EXPERT
Are you using OEM O2s or after market?
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Monday, September 6th, 2010 AT 1:20 PM
Tiny
COISC29
  • MEMBER
The 1 front sensor that I replaced was a Walker oxygen sensor (aftermarket).
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Wednesday, September 8th, 2010 AT 10:41 AM
Tiny
DOCFIXIT
  • EXPERT
Did you have to cut wires and reconnect?
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Wednesday, September 8th, 2010 AT 3:14 PM
Tiny
COISC29
  • MEMBER
No the plug fit perfectly.
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Wednesday, September 8th, 2010 AT 10:12 PM
Tiny
DOCFIXIT
  • EXPERT
Several things can cause codes
leak in air induction
spark plugs
injectors
fuel pressure
distributor
wiring see schematic


https://www.2carpros.com/forum/automotive_pictures/198357_Graphic_610.jpg

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Thursday, September 9th, 2010 AT 10:12 AM

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