95.5-2004 Tacomas & 96-2002 4Runners 4th gen pickups and 3rd gen 4Runners

Check Engine Light HELP...

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Old Feb 6, 2005 | 08:26 AM
  #1  
MTNTOY's Avatar
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From: Durango, CO
Check Engine Light HELP...

First a quick synopsis:
2 weeks ago my check engine light comes on...pull the code: Lean Bank 1 and O2 sensor #1 malfunctioning, so I go ahead and replace both O2 sensors and run some BG cleaner through the tank. CEL comes back on after about a day: Lean Bank 1 and Bank 2...I cleaned my MAF when installing the O2 sensors, so most likely a bad MAF. Just replaced my MAF and now my CEL is back on again!! The OBD reader is getting two codes, both P0171 Too Lean Bank 1.
I’m also getting HORRIBLE gas mileage.

Is there a reason that my computer would be giving two P0171 codes instead of one?
With a new MAF and O2 sensors, What else could be causing this code?
Help!

Is there a way to tell if I need new injectors without taking my fuel system apart?
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Old Feb 6, 2005 | 08:39 AM
  #2  
humanoid's Avatar
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From: Sunny SoCal
Not sure, but I'm sure others will chime in, but did you reset the codes each time you had the CEL codes read?
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Old Feb 6, 2005 | 10:27 AM
  #3  
NathanBERG's Avatar
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From: Washington State
Lightbulb

You should read this Forums Thread on this same Porblem.

http://toyotaownersclub.com/forums/i...showtopic=9206

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Old Feb 7, 2005 | 04:47 AM
  #4  
MTL_4runner's Avatar
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From: Montreal, QC Canada
Originally Posted by MTNTOY
First a quick synopsis:
2 weeks ago my check engine light comes on...pull the code: Lean Bank 1 and O2 sensor #1 malfunctioning, so I go ahead and replace both O2 sensors and run some BG cleaner through the tank. CEL comes back on after about a day: Lean Bank 1 and Bank 2...I cleaned my MAF when installing the O2 sensors, so most likely a bad MAF. Just replaced my MAF and now my CEL is back on again!! The OBD reader is getting two codes, both P0171 Too Lean Bank 1.
I’m also getting HORRIBLE gas mileage.

Is there a reason that my computer would be giving two P0171 codes instead of one?
With a new MAF and O2 sensors, What else could be causing this code?
Help!

Is there a way to tell if I need new injectors without taking my fuel system apart?
Are these OEM sensors? or did you get them aftermarket?
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Old Feb 7, 2005 | 03:28 PM
  #5  
MTNTOY's Avatar
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From: Durango, CO
Yea, they are aftermarket Denso O2 sensors from URD...and yes, the codes were reset
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Old Feb 7, 2005 | 05:45 PM
  #6  
MTNTOY's Avatar
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From: Durango, CO
Bump...anyone...
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Old Feb 7, 2005 | 06:00 PM
  #7  
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From: WA State
Humm, where to start. Vacuum leaks, a leak between the MAF sensor and the throttle body, exhaust leaks before the o2s, bad ground connection to the o2s. Take some brake clean and hose down bank 1 intake manifold, see if the idle changes. Better yet, if you have a scanner, see if your fuel trim numbers change. Start with the simple stuff.

-Wrench
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