4.6L (1996-2004 Modular) Mustang Technical discussions on 1996-2004 4.6 Liter Modular Motors (2V and 4V) within.

2 codes what do they mean?

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Old Jul 17, 2009 | 07:17 PM
  #1  
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Default 2 codes what do they mean?

the light just came on I pulled these

P1131 Lack Of HO2S11 Switch - Sensor Indicates Lean

P1151 Lack Of HO2S21 Switch - Sensor Indicates Lean
Old Jul 17, 2009 | 07:41 PM
  #2  
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It sounds like the long-tube syndrone....been there done that
Old Jul 17, 2009 | 08:10 PM
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I dont understand whats wrong with my longtubes?
Old Jul 17, 2009 | 09:00 PM
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It could be something else wrong but when you did your long tubes did you get a tune for them? They move the O2's downstream which can cause this code. I was getting this too originally when I installed mine. Here is all the other crap it could be though. Check the underlined ones first.

Electrical:
Short to VPWR in harness or HO2S
Water in harness connector
Open/Shorted HO2S circuit
Corrosion or poor mating terminals and wiring
Damaged HO2S
Damaged PCM
Fuel System:
Excessive fuel pressure
Leaking/contaminated fuel injectors
Leaking fuel pressure regulator
Low fuel pressure or running out of fuel
Vapor recovery system
Induction System:
Air leaks after the MAF
Vacuum Leaks
PCV system
Improperly seated engine oil dipstick
EGR System:
Leaking gasket
Stuck EGR valve
Leaking diaphragm or EVR
Base Engine:
Oil overfill
Cam timing
Cylinder compression
Exhaust leaks before or near the HO2S(s)
Old Jul 17, 2009 | 09:15 PM
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In closed loop the PCM expects changes it makes in AFR to be read by the front sensors in after a specific delay that is set in the O2 Transport Delay table. This table specifies a delay time in seconds for load vs. rpm. Stock values range from 0.602s at 10% load and 1000 rpm, to 0.133s at 70% load and 3500 rpm.

When the sensors are relocated further away from the exhaust ports these values need to be increased.
Old Jul 17, 2009 | 09:25 PM
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I have had my longtubes on for almost 3 years now, so I dont know why something would come up now. I will check out the things on that list.
Old Jul 18, 2009 | 01:16 PM
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anybody else?
Old Jul 18, 2009 | 08:46 PM
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As O2 sensors age their response time slows...
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