Fault codes ''failed smog check''

Need help ? Take it to a qualified repair shop that has the diagnostic skill's to find the problem . Just replacing parts is not the way to a fix . The code's don't tell you a part is to be replaced .
P1131 - Lack of HO2S-11 Switch, Sensor Indicates Lean 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 control system no longer detects switching for a calibrated amount of time. See Possible Causes for DTC P1130 P1151 - Lack of HO2S-21 Switch, Sensor Indicates Lean A HEGO sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when fuel control system no longer detects switching for a calibrated amount of time. See Possible Causes for DTC P1130

Hope this helps you or future parties of intrest. P1131 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1 P1151 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 2 I would get under your stang and gently clean outside portion of o2 sensors using a scotch brite. Also if you have so dielectric grease pull electrical connections to o2 sensors clean them and add grease. These trick eliminated the o2 sensor OBD1 codes on my 1987 Ford mustang gt

I will try to paste an article for you. Several sources indicate this is a Bank 2 O2 sensor problem and that it is failing to switch and adjust for the fuel mix. But as you can see, many defects can lead up to this O2 sensor Code 1150.

I would try to use a spray bottle of water and go around the Intake manifold and spray the water while the engine is running. An intake leak will draw water into the engine and change RPM.

If no success then try changing the O2 bank 2 sensor. You may need to wipe the computer and clear the Code. H40 DTCs P1131, P1132, P1151 AND P1152: UPSTREAM HO2S NOT SWITCHING. DTC P1130: FUEL SYSTEM NOT SWITCHING AT FUEL TRIM (RICH OR LEAN)
Diagnostic Trouble Codes (DTCs) P1131 bank 1 (Cylinder 1) and P1151 bank 2 indicate the fuel/air ratio is correcting rich for an overly lean condition. The HO2S voltage is less than 0.45 volt. DTCs P1132 bank 1 (Cylinder 1) and P1152 bank 2 indicate the fuel/air ratio is correcting lean for an overly rich condition. The HO2S voltage is greater than 0.45 volt.
DTC P1130 and P1150 indicate the fuel control system has reached maximum compensation for a lean or rich condition and the HO2S is not switching.
DTC/HO2S Reference List
•HO2S-11 = DTCs P1131, P1132 and P1130
•HO2S-21 = DTCs P1151, P1152 and P1150
Possible causes:
Fuel system
•Excessive fuel pressure.
•Leaking fuel injector(s).
•Leaking fuel pressure regulator.
•Low fuel pressure or running out of fuel.
•Contaminated fuel injector(s)
•Vapor recovery system
Induction system
•Air leaks after the MAF.
•Vacuum leaks (vacuum lines and gaskets).
•Restricted air inlet.
•PCV system.
•Improperly seated engine oil dipstick.
EGR System
•Leaking gasket.
•Stuck open EGR valve.
•Leaking diaphragm.
Base engine
•Oil overfill.
•Cam timing.
•Cylinder compression.
•Exhaust leaks before or near the HO2Ss.
•Check intake air system for leaks, obstructions and damage.
•Check air cleaner element, air cleaner housing for blockage.
•Verify integrity of the PCV system.
•Check for vacuum leaks. )

I don't care how handy you are , that's not going to help you unless you have knowledge of OBD 2 engine management system for your vehicle . Plus having diagnostic test equipment , scan tool to view engine sensor data ., an knowing how to do automotive electrical circuit testing.
Po171 Could be just an O2 sensor problem ,looking at scan data for bank 1 sensor 1 for proper switching , could be a easy find for a trained Tech . You on the other hand could spend hundreds an still not fix the problem .

P0171 - System to Lean (Bank 1) The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. For lean and rich DTCs:

• 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 HO2Ss.

P1130 - Lack of HO2S-11 Switch, Fuel Trim at Limit The HEGO Sensor is monitored for switching. The test fails when the HO2S fails to switch due to circuit or fuel at or exceeding a calibrated limit.

• 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)

A fuel control HO2S PID switching across 0.45 volt from 0.2 to 0.9 volt indicates a normal switching HO2S. P1131 - Lack of HO2S-11 Switch, Sensor Indicates Lean 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 control system no longer detects switching for a calibrated amount of time. See Possible Causes for DTC P1130
P1151 - Lack of HO2S-21 Switch, Sensor Indicates Lean A HEGO sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when fuel control system no longer detects switching for a calibrated amount of time. See Possible Causes for DTC P1130 006 O2 Sensor Signal Analysis

P1131-- Lack of HO2S-11 Switch (lean)
P1151--Lack of HO2S-12 Switch (lean)

There are at least 26 possible causes in the
Diagnostic Trouble Code Chart

That isn't going to be a driveway job,
your going to resolve

H40 DTCs P1131, P1132, P1151 AND P1152: UPSTREAM HO2S NOT SWITCHING. DTC P1130: FUEL SYSTEM NOT SWITCHING AT FUEL TRIM (RICH OR LEAN)

Diagnostic Trouble Codes (DTCs) P1131 bank 1 (Cylinder 1) and P1151 bank 2 indicate the fuel/air ratio is correcting rich for an overly lean condition. The HO2S voltage is less than 0.45 volt. DTCs P1132 bank 1 (Cylinder 1) and P1152 bank 2 indicate the fuel/air ratio is correcting lean for an overly rich condition. The HO2S voltage is greater than 0.45 volt.
DTC P1130 and P1150 indicate the fuel control system has reached maximum compensation for a lean or rich condition and the HO2S is not switching.
DTC/HO2S Reference List

• HO2S-11 = DTCs P1131, P1132 and P1130
• HO2S-21 = DTCs P1151, P1152 and P1150
Possible causes:
Fuel system

• Excessive fuel pressure.
• Leaking fuel injector(s).
• Leaking fuel pressure regulator.
• Low fuel pressure or running out of fuel.
• Contaminated fuel injector(s)
• Vapor recovery system
Induction system

• Air leaks after the MAF.
• Vacuum leaks (vacuum lines and gaskets).
• Restricted air inlet.
• PCV system.
• Improperly seated engine oil dipstick.
EGR System

• Leaking gasket.
• Stuck open EGR valve.
• Leaking diaphragm.
Base engine

• Oil overfill.
• Cam timing.
• Cylinder compression.
• Exhaust leaks before or near the HO2Ss.
• Check intake air system for leaks, obstructions and damage.
• Check air cleaner element, air cleaner housing for blockage.
• Verify integrity of the PCV system.
• Check for vacuum leaks.

P1131 and P1151 are for the oxygen sensors. one in the exhaust at the firewall and one at the radiator off the manifold. When both go off though at the same time I would suspect a vacuum leak after the MAF sensor(mass air flow), if only one code then suspect that O2 oxygen sensor

DTC P1131 DTC P1151 indicates the system is correcting RICH for an overly LEAN condition. The Heated Oxygen Sensor (HO2S) voltage is less than 0.45 volts. This is usually due to a vacuum leak after the MAF. It can also be caused by a bad PCV valve or PCV system hose. It can also be caused by low fuel pressure or a plugged injector.

Start with the simple and clean the MAF and the IAT sensor. In simple terms, the engine is running lean and is being compensated by the ECM. P1131 is bank 1 and P1151 is bank2

Good luck and keep me posted.

TSB
05-22-6
ISSUE:
Some 2001-2003 F-150, 2004 F-150 Heritage and 2001-2003 E-150/250 vehicles equipped with a 4.2L engine may exhibit the malfunction indicator lamp (MIL) on with diagnostic trouble codes (DTCs) P1131 and/or P1151 (system too lean bank 1 or 2). This condition may be due to leaking isolator bolts/port gaskets in the upper-to-lower intake manifold mounting area. This condition is sometimes intermittent and may not be apparent on a warmed-up engine.


SERVICE PROCEDURE

Perform a self test. If DTC P1131 and/or P1151 are the only codes stored in the powertrain control module (PCM) proceed to Step 2. If any additional DTCs are present, follow normal diagnostic procedures found in the PC/ED Manual.

Remove the upper intake and replace only the port gaskets (9H486) and isolator bolt assemblies (9S479). The new isolator bolt assemblies use a rubber material that is green in color, do not install the old isolator bolt assemblies with the black rubber material. Do not replace any other intake parts or gaskets.
While the upper intake manifold is removed, check the exhaust gas recirculation (EGR) orifices that are pressed into each primary port of the lower intake manifold. If any of the orifices are plugged with soot, clean and unplug them with a pick and solvent.

PART NUMBER PART NAME
1L3Z-9H486-AA Port Gasket
3F2Z-9S479-AA Isolator Bolt

If both, P1131 and P1151 trouble codes are set at the same time, the problem will most likely be attributed to a vacuum leak past the MAF (Mass Air Flow) sensor or something else that would likely affect BOTH banks. If the problem is only causing one code or the other, but NOT both, the problem will most likely be something that would affect one bank, like a bad O-2 sensor or a fuel injector; the most common cause of a single code either the P1131 or P1151 in my experience has been a bad Oxygen sensor.