obd 2 system
Senior Member
Joined: Jan 1999
Posts: 165
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From: Lexington, SC USA
per Chilton's: p1131 = lack of upstream heated oxygen sensor (HO2S 11) Switch, Sensor indicates lean (bank 1)
per Chilton's: p0131 = O2 sensor circuit low voltage (bank 1 sensor 1)
to fix, replace that O2 sensor. I believe it will be the one on the passenger side in front of the catalytic converter. This always seems to be the first sensor to go. I figure it is because of the air conditioning condensor dripping water on it.
-Michael
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Oxford White 2001 SuperCrew Lariat 4X2
MODS:
Roadmaster Active Suspension
Retrax bed cover
Ultimate Linings sprayed in bed liner
per Chilton's: p0131 = O2 sensor circuit low voltage (bank 1 sensor 1)
to fix, replace that O2 sensor. I believe it will be the one on the passenger side in front of the catalytic converter. This always seems to be the first sensor to go. I figure it is because of the air conditioning condensor dripping water on it.
-Michael
------------------
Oxford White 2001 SuperCrew Lariat 4X2
MODS:
Roadmaster Active Suspension
Retrax bed cover
Ultimate Linings sprayed in bed liner
Senior Member
Joined: Feb 2001
Posts: 224
Likes: 0
From Ford manual, just don't ask me what it all means.
P0131- HO2S Sensor Circuit Out of Range Low Voltage (HO2S-11)
Description-
The HO2S sensor is monitored for a negative voltage known as characteristic shift downward (CSD). If the sensor is thought to be switching from 0 volts to -1 volts during testing, the PCM will use this input and remain in fuel control.
Possible Causes-
*Contaminated HO2S (water, fuel, etc.)
*Crossed HO2S signal/signal return wiring.
P1131- Lack of HO2S-11 Switch, Sensor Indicates Lean
Description-
A HEGO sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when the fuel system no longer detects switching for a calibrated amount of time.
Possible Causes-
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 EGR
Base Engine
*Oil overfill
*Cam timing
*Cylinder compression
*Exhaust leaks before or near HO2S(s)
P0131- HO2S Sensor Circuit Out of Range Low Voltage (HO2S-11)
Description-
The HO2S sensor is monitored for a negative voltage known as characteristic shift downward (CSD). If the sensor is thought to be switching from 0 volts to -1 volts during testing, the PCM will use this input and remain in fuel control.
Possible Causes-
*Contaminated HO2S (water, fuel, etc.)
*Crossed HO2S signal/signal return wiring.
P1131- Lack of HO2S-11 Switch, Sensor Indicates Lean
Description-
A HEGO sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when the fuel system no longer detects switching for a calibrated amount of time.
Possible Causes-
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 EGR
Base Engine
*Oil overfill
*Cam timing
*Cylinder compression
*Exhaust leaks before or near HO2S(s)