Fuel System Not Switching At Fuel Trim (Rich Or Lean)

• P1130 indicates HO2S-11 (front RH) fails to switch due to circuit or fuel at or exceeding a calibrated limit.
• P1150 indicates HO2S-21 (front LH) fails to switch due to circuit or fuel at or exceeding a calibrated limit.

• 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)
• Induction system:
  • Air leaks after the mass air flow (MAF)
  • Vacuum leaks (vacuum lines and gaskets)
  • Positive crankcase ventilation (PCV) system
  • Improperly seated engine oil dipstick
• Exhaust gas recirculation (EGR) system:
  • Leaking gasket
  • Stuck open EGR valve
• Base engine:
  • Oil overfill
  • Cam timing
  • Cylinder compression
  • Exhaust leaks before or near HO2S(s)
• Electrical:
  • Short to VPWR in harness or HO2S
  • Water in harness connector
  • Open/shorted HO2S
  • Damaged HO2S
  • Damaged powertrain control module (PCM)

• See FUEL SYSTEM MONITOR .

See ENGINE OBD II MONITORS .

HO2S Description 

• Detects the presence of oxygen in the exhaust and produces a variable voltage (0.0-1.1 V) according to the amount of oxygen detected.
  • A high concentration of oxygen (lean air/fuel ratio) in the exhaust produces a low voltage signal (less than 0.4 V).
  • A low concentration of oxygen (rich air/fuel ratio) in the exhaust produces a high voltage signal (greater than 0.6 V).
• Provides feedback to the PCM indicating air/fuel ratio in order to achieve a near stoichiometric air/fuel ratio of 14.7:1 during closed loop engine operation.

• Was the PCM quick test performed?

• Are any other DTCs present during PCM quick test? 

• Is DTC P1130 or P1150 on FREEZE FRAME DATA? 

• Check air cleaner element and air cleaner housing for blockage.
• Check air intake system for leaks and damage.
• Verify integrity of PCV system.
• Check for vacuum leaks.
• Are any of the above concerns present? 

• Inspect HO2S harness for chafing, burned wiring or other damage and repair as necessary.
• Disconnect the suspect HO2S from vehicle harness.
• Connect multimeter to HO2S Signal and HO2S SIG RTN or HO2S GND at the HO2S sensor connector.
• Run engine at 2, 000 rpm for three minutes.
• Run KOER self-test and monitor HO2S voltage.
• Key OFF.
• Is voltage greater than 0.5 volt during or at the end of self-test? 

• Key on, engine running (KOER).
• Engine at operating temperature.
• Using WDS or equivalent tester, select Diagnostic Data Link.
• Select PCM.
• Select PID/Data Monitor and Record.
• Access O2S11 (Front RH) or O2S21 (Front LH) PID and monitor while wiggling, bending and shaking small sections of the engine harness from the HO2S to the PCM.
• Key OFF.
• Does the HO2S voltage stay high (greater than 0.45 V) or low (less than 0.45 V)? 

• Install fuel pressure gauge.
• Key on, engine off (KOEO).
• Using WDS or equivalent tester, select Diagnostic Data Link.
• Select PCM.
• Select Active Command Modes.
• Access output test mode and run the fuel pump to obtain maximum fuel pressure.
  NOTE:

  • The fuel pump will only operate for approximately 8 seconds when output test mode is selected and activated.
• Is the fuel pressure 207-448 kPa (30-65 psi) for 3.0L / 4.0L or 240-380 kPa (35-55 psi) for 2.3L? 

• Access INJ1F-INJ16F PIDs.
• Is an injector(s) fault present? 

• Disconnect PCM.
• Install breakout box, leave PCM disconnected.
  NOTE:

  • Use the injector fault PID to determine the fuel injector circuit(s) requiring testing.
• Measure resistance of suspect fuel injector between suspect INJ circuit PCM test pin and PCM test pin 71 (VPWR).
• Is the resistance between 11.0-18.0 ohms for 4.0L or 8.5-15.5 ohms for 3.0L or 11.0-13.0 ohms for 2.3L? 

• Disconnect fuel injector harness connector at the suspect fuel injector.
• Measure resistance of VPWR circuit between PCM test pin 71 (VPWR) and the fuel injector harness connector.
• Measure resistance of INJ circuit between the appropriate PCM test pin and the fuel injector harness connector.
• Is each resistance less than 5.0 ohms? 

• Measure resistance between suspect INJ circuit PCM test pin and PCM test pin 71 (VPWR).
• Measure resistance between suspect. INJ circuit PCM test pin and PCM test pin 103(PWRGND).
• Is each resistance greater than 10K ohms? 

• Use a fuel injector tester to flow test the fuel injectors according to the instructions for the tester.
  • Flow rate specification is 5.5 kg/hr (12 lb/hr) for 3.0L 8.7 kg/hr (19 lb/hr) for 4.0L, 9.6 kg/hr (21 lb/hr) for 2.3L
• Is the leakage and flow within specification? 

• Inspect the following areas for signs of air leaks:
  • Inlet tube(s) from air cleaner to throttle body
  • Gaskets which seal upper and lower intake manifold
  • Vacuum hoses and lines for cracks and proper connections
  • PCV system
• Are there any signs of leaks or damage? 

• Check cylinder compression. See ENGINE COMPONENT TEST .
• Are cylinder compression readings within specification? 

• Using WDS or equivalent tester, select Diagnostic Data Link.
• Select PCM.
• Select PID/Data Monitor and Record.
• Access O2S11 (Front RH) or O2S21 (Front LH) PID.
• While observer views PID, test drive vehicle under different road conditions in an attempt to simulate the original fault.
• Does HO2S appear to switch properly? 

• Connect all disconnected connectors.
• Clear DTCs from PCM memory using WDS or equivalent tester.
• Perform EVAP System Monitor Drive Cycle. See DRIVE CYCLES .
• Retrieve pending code.
• Is same DTC present? 

• Perform PCM quick test.
• Is any DTC present?