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

DTC P1130, P1150 DETECTION CONDITION AND POSSIBLE CAUSE

DTC P1130, P1150 FUEL SYSTEM NOT SWITCHING AT FUEL TRIM (RICH OR LEAN)
DETECTION CONDITION 
  • 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.
POSSIBLE CAUSE 
  • 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 MAF.
    • Vacuum leaks (vacuum lines and gaskets).
    • 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 HO2S(s).
  • Electrical:
    • Short to VPWR in harness or HO2S.
    • Water in harness connector.
    • Open/shorted HO2S.
    • Damaged HO2S.
    • Damaged PCM.
HINT  HO2S Sensor 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.
G03988149Courtesy of MAZDA MOTORS CORP.
DTC P1130, P1150 INSPECTION

STEP INSPECTION ACTION
1
  • Was PCM Quick Test performed? 
 Yes Go to next step.
No Perform PCM Quick Test.
2 VERIFY RELATED PENDING AND STORED DTCs
  • Are any other DTCs present during PCM Quick Test? 
 Yes Go to appropriate DTC troubleshooting procedures.
No Go to next step.
3 IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA
  • Is DTC P1130 or P1150 on FREEZE FRAME DATA? 
 Yes Go to next step.
No Go to troubleshooting procedures for DTC on FREEZE FRAME DATA.
See FUEL INJECTOR MALFUNCTION .
4 DTCs P1130 AND P1150: FUEL SYSTEM NOT SWITCHING AT FUEL TRIM (RICH OR LEAN)
NOTE: It is necessary to address all Continuous Memory Ignition (P0350-P0354) and Misfire DTCs (P0300-P0306) received during Continuous Memory testing before addressing any KOER HO2S DTCs.
  • 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? 
 Yes Repair as necessary.
Go to step 16.
No Go to next step.
5 CHECK HO2S ABILITY TO GENERATE A VOLTAGE GREATER THAN 0.5 VOLT
  • Inspect HO2S harness for wear from rubbing, burned wiring or other damage and repair as necessary.
  • Disconnect the suspect HO2S from vehicle harness.
  • Connect multimeter to HO2S SIG and HO2S SIG RTN at the HO2S sensor connector.
  • Run engine at 2, 000 rpm for three minutes.
  • Run KOER Self Test and monitor HO2S voltage.
  • Key OFF.
  • Was voltage greater than 0.5 V during or at the end of Self Test? 
 Yes Go to next step.
No Replace HO2S.
See HEATED OXYGEN SENSOR (HO2S) in REMOVAL, OVERHAUL AND INSTALLATION article in Engine Performance .
Go to step 16.
6 MONITOR HO2S (PID) FOR PROPER SWITCHING
  • Key ON, Engine Running (KOER).
  • Engine at operating temperature.
  • Access O2S11 (Front RH) or O2S21 (Front LH) PID with NGS Tester and monitor while wiggling, bending and shaking small sections of the engine harness from the HO2S to the PCM.
  • Key OFF.
  • Did the HO2S voltage stay high (greater than 0.45 V) or low (less than 0.45 V)? 
 Yes Isolate cause of lack of HO2S switching and repair as necessary.
Go to step 16.
No Go to next step.
7 CHECK FUEL PRESSURE
WARNING: The fuel system is pressurized when the engine is not running. To prevent injury or fire, use caution when working on the fuel system.
  • Install fuel pressure gauge.
  • Key ON, Engine OFF (KOEO).
  • 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 30--65 psi (207--448 kPa)? 
 Yes Fuel system is capable of required fuel pressure.
Go to next step.
No See TEST 5: FUEL DELIVERY SYSTEM .
8 CHECK INJECTOR FAULT PIDS
  • Access INJ1F-INJ6F PIDs with NGS Tester.
  • Is an injector fault present? 
 Yes Go to next step.
No Go to step 12.
9 CHECK FUEL INJECTOR(S) AND HARNESS RESISTANCE
NOTE: This erases Continuous Memory DTCs.
  • 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? 
 Yes Replace PCM. See COMPUTERIZED ENGINE CONTROLS .
Go to step 16.
No Go to next step.
10 CHECK FUEL INJECTOR HARNESS RESISTANCE
  • Disconnect fuel injector harness connector at the suspect fuel injector.
  • Measure resistance of suspect fuel injector between suspect INJ circuit PCM test pin and PCM test pin 71 (VPWR).
  • Measure resistance of suspect fuel injector between suspect INJ circuit PCM test pin and PCM test pin 103 (PWR GND).
  • Is each resistance less than 5.0 ohms? 
 Yes Go to next step.
No Repair open harness circuit.
Go to step 16.
11 CHECK FUEL INJECTOR HARNESS CIRCUIT FOR SHORT TO POWER AND GROUND
  • 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 (PWR GND).
  • Is each resistance greater than 10K ohms? 
 Yes Go to next step.
No Repair short circuit.
Go to step 16.
12 FLOW TEST FUEL INJECTOR(S)
  • Use a fuel injector tester to flow test the fuel injectors according to the instructions for the tester.
  • Flow rate specification is 14 lb/hr (6.4 kg/hr) for gas engines and 19 lb/hr (8.6 kg/hr) for the 3.0L Flexible Fuel engine.
  • Is the leakage and flow within specification? 
 Yes Go to next step.
No Replace fuel injector(s).
See FUEL RAILS & INJECTORS in REMOVAL, OVERHAUL, AND INSTALLATION article in Engine Performance .
Go to step 16.
13 INSPECT INDUCTION SYSTEM FOR AIR LEAKS
  • 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? 
 Yes Repair as necessary.
Go to step 16.
No Go to next step.
14 CHECK CYLINDER COMPRESSION
  • Check cylinder compression.

    See ENGINE COMPONENT TESTS .

  • Are cylinder compression readings within specification? 
 Yes Go to next step.
No Repair as necessary.
Go to step 16.
15 TEST DRIVE WHILE MONITORING HO2S PID FOR PROPER SWITCHING
NOTE: This step requires an observer to monitor PID for proper operation.
  • 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? 
 Yes Unable to duplicate fault.
Go to step 16.
No Replace HO2S.
See HEATED OXYGEN SENSOR (HO2S) in REMOVAL, OVERHAUL AND INSTALLATION article in Engine Performance .
Go to step 16.
16 DRIVE CYCLE
  • Make sure to reconnect all disconnected connectors.
  • Clear DTCs from PCM memory using NGS tester generic OBD-II function.
  • Perform Fuel Monitor or HO2S Monitor Drive Cycle.
    • See DRIVE CYCLES .
    • Retrieve pending code.
    • Is same DTC present? 
 Yes Replace PCM. See COMPUTERIZED ENGINE CONTROLS .
Go to next step.
No Go to next step.
17 VERIFY REPAIR
  • Perform PCM Quick Test.
  • Is any DTC present? 
 Yes Go to applicable DTC inspection.
No Troubleshooting complete.
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