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Home >> Mazda >> 2008 >> Tribute Hybrid Touring, AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Pinpoint Tests - Hybrid >> H: Fuel Control >> Test Procedure

Test Procedure

  1. H1: DIAGNOSTIC TROUBLE CODES (DTCS) P0171, P0172, P2195, P2196, P2270, AND P2271: CHECK FOR SELF-TEST DTCS 
    • Are any of the following DTCs present during the PCM self-test: P0171, P0172, P2195, P2196, P2270, or P2271? 
  2. H2: DTCS P0171 OR P2195: LEAN SYSTEM DTCS 
    NOTE: Do not clear the DTCs or reset the keep alive memory (KAM).
    • Access the PCM and record the ECT PID from the freeze frame data. The freeze frame data is used to recreate the concern.
    • Retrieve and record the self-test DTCs.
    • Are any DTCs present other than P0171 or P2195? 
  3. H3: CARRY OUT A VISUAL INSPECTION ON THE INTAKE AIR SYSTEM AND ALL VACUUM HOSES 
    • Key in OFF position.
    • Check the intake air system for leaks, obstructions, and damage.
    • Inspect the entire length of all the vacuum hoses for:
      • proper connections
      • damage or cracks
      • damaged or cracked vacuum tees
    • Verify the integrity of the positive crankcase ventilation (PCV) system.
    • Verify the proper PCV valve part number.
    • Is a concern present? 
    • Yes:  GO to  H6.
    • No:  GO to  H4.
  4. H4: CHECK FOR THE PRESENCE OF A VACUUM LEAK 
    NOTE: Fuel trim values at idle are more sensitive to a vacuum leak. The vacuum leak (unmetered air) represents a larger portion of the total air flow at idle than at part throttle.
    NOTE: The barometric pressure (BARO) PID is not a recommended PID to monitor when diagnosing a vacuum leak. Barometric pressure is calculated during high engine load, when the vacuum leak represents a small portion of the total air flow.
    NOTE: When calculating the total fuel correction in the following steps, if LONGFT1 equals +13% and SHRTFT1 equals +23%, the total fuel correction for bank 1 equals +36%. If LONGFT1 equals +24% and SHRTFT1 equals -3% the total fuel correction for bank 1 equals +21%.
    NOTE: If the freeze frame ECT PID is available, stabilize the engine at the temperature recorded by the freeze frame ECT PID. If the freeze frame ECT PID is not available, maintain the engine coolant temperature between 82°C - 101°C (180°F - 215°F) and the intake air temperature less than 46°C (115°F).
    • Key ON, engine running.
    • Access the PCM and monitor the ECT, CHT, IAT, LONGFT1 and SHRTFT1 PIDs.
    • Allow the engine to stabilize at the temperature necessary to recreate the concern.
    • Mathematically add and record the LONGFT PID value to the SHRTFT PID value, for a total fuel correction at idle.
    • Increase the engine speed to 2,500 RPM for 10 seconds.

      Record the LONGFT1 and SHRTFT1 PID values.

    • Mathematically add and record the LONGFT PID value to the SHRTFT PID value, for a total fuel correction at 2,500 RPM.
    • Is the total fuel correction value difference, between idle and 2,500 RPM, less than 15 percent? 
    • Yes:  No vacuum leak is present.

      For DTC P0171, GO to  H15.

      For DTC P2195, GO to  H9.

    • No:  GO to  H5.
  5. H5: LOCATE THE VACUUM LEAK 
    CAUTION: Do not clamp or pinch a hard plastic hose. Use a vacuum cap or equivalent to restrict the hose.
    NOTE: Restricting the EVAP vapor hose while the EVAP emission canister is purging may shift the SHRTFT. Carry out a visual inspection as necessary.
    NOTE: When monitoring for a decrease in the SHRTFT1 PID in the following steps, if SHRTFT1 is +15%, but when the hose is restricted SHRTFT1 decreases to -7%, the decrease in the SHRTFT1 PID equals 22%.
    • Locate the vacuum tees for the intake air and PCV systems.
    • Access the PCM and monitor the SHRTFT1 PID.
    • Restrict the vacuum lines one at a time for 30 seconds. If a vacuum leak is present, the SHRTFT1 PID value decreases as the hose is restricted.
    • Is the decrease in the SHRTFT1 PID greater than 15 percent when one of the vacuum hoses is restricted? 
    • Yes:  GO to  H6.
    • No:  INSPECT the intake air system for a vacuum leak in the intake manifold or intake gaskets. REPAIR as necessary.

      For repair verification, GO to  H6.

  6. H6: VACUUM LEAK REPAIR VERIFICATION 
    NOTE: If the freeze frame ECT PID is available, stabilize the engine at the temperature recorded by the freeze frame ECT PID. If the freeze frame ECT PID is not available, maintain the engine coolant temperature between 82°C - 101°C (180°F - 215°F) and the intake air temperature less than 46°C (115°F).
    • Access the PCM and monitor the SHRTFT1 PID.
    • Allow the engine to stabilize at the temperature necessary to recreate the concern.
    • Record the SHRTFT1 PID value.
    • Key in OFF position.
    • Repair the vacuum leak.
    • Key ON, engine running.
    • Allow the engine to stabilize at the temperature necessary to recreate the concern.
    • Access the PCM and monitor the SHRTFT1 PID.
    • Compare the recorded SHRTFT1 PID value, prior to the vacuum leak repair, to the current SHRTFT1 PID value.
    • Is the decrease in the SHRTFT1 PID greater than 15 percent? 
  7. H7: DTCS P0172 OR P2196: RICH SYSTEM DTCS 
    NOTE: Do not clear the DTCs or reset the KAM.
    • Access the PCM and record the freeze frame data.
    • Retrieve and record the self-test DTCs.
    • Are any DTCs present other than P0172 or P2196? 
  8. H8: INSPECT THE ENTIRE INTAKE AIR SYSTEM FOR DEBRIS, BLOCKAGE OR OTHER DAMAGE 
    • Check the intake air system for obstructions, restrictions, and damage.
    • Check the air filter element and housing for blockage.
    • Is a concern present? 
    • Yes:  REPAIR as necessary.

      CLEAR the DTCs. REPEAT the self-test.

    • No:  For DTC P0172, GO to  H15.

      For DTC P2196, GO to  H13.

  9. H9: CHECK THE HO2S AND SIGRTN CIRCUIT(S) FOR AN OPEN IN THE HARNESS 
    • Key in OFF position.
    • Disconnect the HO2S related to the current DTC.
    • PCM connector disconnected.
    • Measure the resistance between:
      (+) HO2S Connector, Harness Side (-) PCM Connector, Harness Side
      HO2S Signal HO2S Signal
      SIGRTN SIGRTN - Pin E41
    • Are the resistances less than 5 ohms? 
    • Yes:  GO to  H10.
    • No:  REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.
  10. H10: CHECK THE HO2S CIRCUIT FOR A SHORT TO SIGRTN IN THE HARNESS 
    • Measure the resistance between:
      (+) HO2S Connector, Harness Side (-) HO2S Connector, Harness Side
      HO2S Signal SIGRTN
    • Is the resistance greater than 10K ohms? 
    • Yes:  GO to  H11.
    • No:  REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.
  11. H11: CHECK THE HO2S CIRCUIT FOR A SHORT TO GROUND IN THE HARNESS 
    • Measure the resistance between:
      (+) HO2S Connector, Harness Side (-)
      HO2S Signal Ground
    • Is the resistance greater than 10K ohms? 
    • Yes:  GO to  H12.
    • No:  REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.
  12. H12: HO2S CIRCUIT TEST (WITH LEAN DTCS) 
    • PCM connector connected.
    • Connect a 5 amp fused jumper wire between the following:
      Point A HO2S Connector, Harness Side Point B HO2S Connector, Harness Side
      HO2S Signal VPWR
    • Key ON, engine OFF.
    • Access the PCM and monitor the HO2S Signal PID.
    • Is the voltage greater than 1.3 V? 
    • Yes:  GO to  H15.
    • No:  GO to  H33.
  13. H13: HO2S CIRCUIT TEST (WITH RICH DTCS) 
    • Disconnect the HO2S related to the current DTC.
    • Key ON, engine OFF.
    • Access the PCM and monitor the HO2S Signal PID.
    • Is the voltage less than 0.2 V? 
    • Yes:  GO to  H15.
    • No:  GO to  H14.
  14. H14: CHECK THE HO2S CIRCUIT FOR A SHORT TO THE VPWR OR HEATER IN THE HARNESS 
    • Key in OFF position.
    • PCM connector disconnected.
    • Measure the resistance between:
      (+) PCM Connector, Harness Side (-) PCM Connector, Harness Side
      HO2S Signal HO2S Heater
      HO2S Signal VPWR - Pin B35
    • Are the resistances greater than 10K ohms? 
    • Yes:  GO to  H33.
    • No:  REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.
  15. H15: CHECK THE FUEL PRESSURE 
    WARNING: When checking the fuel system remember that the fuel system may still be pressurized when the engine is switched off. Always follow the instructions related to fuel system pressure relief. All fuel handling safety precautions must be observed. Failure to follow these instructions may result in personal injury.
    NOTE: During output state control, the fuel pump stays commanded on for only about 5 seconds.
    • Remove the jumper wire(s).
    • HO2S connector connected.
    • Mechanical fuel pressure gauge connected.
    • Key ON, engine OFF.
    • Access the PCM and control the FP PID.
    • Run the fuel pump to obtain maximum fuel pressure.
    • Is the fuel pressure between 138-517 kPa (20-75 psi)? 
  16. H16: CHECK THE FUEL SYSTEM FOR PRESSURE STABILITY - FAST LEAKDOWN 
    NOTE: When the fuel pump is commanded off, the fuel pressure may substantially decrease and then stabilize.
    NOTE: During output state control, the fuel pump stays commanded on for only about 5 seconds.
    • Key in OFF position.
    • Key ON, engine OFF.
    • Access the PCM and control the FP PID.
    • Run the fuel pump to obtain maximum fuel pressure.
    • Command the fuel pump off.
    • Allow the fuel pressure to stabilize.
    • Record the stabilized reading.
    • Monitor the fuel pressure for 10 seconds.
    • Does the fuel pressure remain within 34 kPa (5 psi) of the recorded reading after 10 seconds? 
    • Yes:  GO to  H18.
    • No:  GO to  H17.
  17. H17: CHECK FOR AN EXTERNAL FUEL LEAK 
    • Inspect the fuel tank, lines, and filler pipe for a fuel leak.
    • Is a concern present? 
  18. H18: CHECK THE FUEL SYSTEM FOR PRESSURE STABILITY - SLOW LEAKDOWN 
    • Continue to monitor the fuel pressure for 1 minute.
    • Is the fuel pressure greater than 275 kPa (40 psi) after 1 minute? 
    • Yes:  GO to  H19.
    • No:  GO to  HC7.
  19. H19: FLOW TEST 
    • Key in OFF position.
    • PCM connector connected.
    • Flow test the injector using the fuel injector tester.
    • Is the flow rate for each injector within specification? 
  20. H20: CHECK THE HO2S OUTPUT VOLTAGE 
    • HO2S connector disconnected.
    • Visually inspect the HO2S circuit for exposed wiring, contamination, corrosion and correct assembly. Repair as necessary.
    • Measure the voltage between:
      (+) HO2S Connector, Component Side (-) HO2S Connector, Component Side
      HO2S Signal SIGRTN
    • Increase the engine speed to 2,000 RPM for 3 minutes.
    • Carry out the KOER self-test.
    • Monitor the signal voltage during the self-test.
    • Is the voltage greater than 0.5 volt at any time during the self-test? 
  21. H21: ATTEMPT TO RETRIEVE DTC P2195 
    • HO2S connector disconnected.
    • Connect a 5 amp fused jumper wire between the following:
      Point A HO2S Connector. Harness Side Point B Vehicle Battery
      HO2S Signal Negative terminal
    • Carry out the KOER self-test.
    • Is DTC P2195 present? 
    • Yes:  GO to  H22.
    • No:  GO to  H33.
  22. H22: HO2S VOLTAGE CHECK 
    • Key in OFF position.
    • Remove the jumper wire(s).
    • HO2S connector disconnected.
    • Increase the engine speed to 2,000 RPM for 30 seconds.
    • Measure the voltage between:
      (+) HO2S Connector, Component Side (-) HO2S Connector, Component Side
      HO2S Signal SIGRTN
    • Carry out the KOER self-test.
    • Monitor the signal voltage during the self-test.
    • Is the voltage less than 0.4 volt at any time during the self-test? 
  23. H23: CARRY OUT A THOROUGH WIGGLE TEST ON THE HO2S HARNESS 
    • Key in OFF position.
    • HO2S connector connected.
    • Key ON, engine running.
    • Engine at normal operating temperature.
    • Access the PCM and monitor the HO2S Signal PID.
    • Wiggle, shake, and bend small sections of the wiring harness while working from the sensor to the PCM.
    • While monitoring the HO2S PID, does the HO2S stop switching? 
    • Yes:  ISOLATE the concern and REPAIR as necessary.

      CLEAR the DTCs. REPEAT the self-test.

    • No:  GO to  H24.
  24. H24: TEST DRIVE THE VEHICLE WHILE MONITORING THE HO2S PID FOR SWITCHING 
    • Access the PCM and monitor the HO2S Signal and FUELSYS PIDs.
    • Start the engine and let idle until the vehicle goes into the closed loop fuel condition.
    • Drive the vehicle in a manner consistent with the freeze frame data in an attempt to simulate the original concern.
    • Does the HO2S PID switch? 
  25. H25: DTCS P2270 OR P2271: HO2S LACK OF SWITCHES STUCK LEAN OR RICH 
    NOTE: Address all continuous memory ignition and misfire DTCs before any KOER HO2S DTCs.
    • Key in OFF position.
    • Visually inspect for:
      • pinched, shorted, and corroded wiring and pins
      • oil or water contamination
      • crossed sensor wires
      • contaminated or damaged sensor
    • Is a concern present? 
    • Yes:  REPAIR as necessary. CLEAR the DTCs. REPEAT the self-test.
    • No:  For KOER DTCs P2270 or P2271, GO to  H27.

      For continuous memory DTCs P2270 or P2271, GO to  H26.

  26. H26: CHECK FOR KOER DTCS 
    • Key ON, engine OFF.
    • Clear the DTCs.
    • Key ON, engine running.
    • Run the engine at approximately 2,000 RPM. Maintain the engine speed for 3 minutes.
    • Retrieve the continuous memory DTCs.
    • Are DTCs P2270 or P2271 present? 
    • Yes:  GO to  H27.
    • No:  Unable to duplicate or identify the concern at this time.

      GO to PINPOINT TEST Z .

  27. H27: CHECK THE HO2S SIGNAL LEVEL TOO HIGH 
    NOTE: Fuel calculations can be affected by unmetered air leaks.
    • Key in OFF position.
    • Carefully inspect the following areas for potential air leaks:
      • hoses connecting to the mass air flow (MAF) sensor assembly
      • hoses connecting to the throttle body
      • intake manifold gasket leaks
      • PCV disconnected.
      • the vacuum lines are disconnected
      • improperly seated engine oil dipstick, tube or oil fill cap
      • exhaust leaks at flanges and gaskets
    • With the vehicle in NEUTRAL, position it on a hoist. Refer to the JACKING and LIFTING for the locations of the lifting points.
    • Visually inspect for:
      • exhaust leaks at flanges and gaskets
      • HO2S not tightened to specification
      • physical exhaust system concerns
      • aftermarket exhaust
      • punctures or cracks in the catalyst
    • Is a concern present? 
    • Yes:  REPAIR as necessary.

      CLEAR the DTCs. REPEAT the self-test.

    • No:  GO to  H28.
  28. H28: CHECK FOR SHORTS BETWEEN CIRCUITS IN THE HO2S HARNESS 
    • PCM connector disconnected.
    • Disconnect the HO2S harness connector.
    • Measure the resistance between:
      (+) PCM Connector, Harness Side (-) Vehicle Battery
      HO2S Signal Negative terminal
    • Measure the resistance between:
      (+) PCM Connector, Harness Side (-) PCM Connector, Harness Side
      HO2S Signal SIGRTN - Pin E41
      HO2S Signal VPWR - Pin B35
      HO2S Signal HO2S Heater
    • Are the resistances greater than 10K ohms? 
    • Yes:  GO to  H29.
    • No:  REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.
  29. H29: CHECK THE HO2S CIRCUIT FOR AN OPEN IN THE HARNESS 
    • Measure the resistance between:
      (+) PCM Connector, Harness Side (-) HO2S Connector, Harness Side
      HO2S Heater HO2S Heater
      VPWR - Pin B35 VPWR
      HO2S Signal HO2S Signal
      SIGRTN - Pin E41 SIGRTN
    • Are the resistances less than 5 ohms? 
    • Yes:  GO to  H30.
    • No:  REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.
  30. H30: CHECK THE HO2S CIRCUIT VOLTAGE 
    • PCM connector connected.
    • HO2S connector connected.
    • Key ON, engine running.
    • Access the PCM and monitor the HO2S Signal PID.
    • Is the voltage greater than 1.5 V? 
    • Yes:  GO to  H32.
    • No:  GO to  H31.
  31. H31: CHECK THE HO2S CIRCUIT VOLTAGE 
    • Key in OFF position.
    • PCM connector connected.
    • HO2S connector disconnected.
    • Connect a 5 amp fused jumper wire between the following:
      Point A HO2S Connector, Harness Side Point B HO2S Connector, Harness Side
      HO2S Signal VPWR
    • Key ON, engine OFF.
    • Access the PCM and monitor the HO2S Signal PID.
    • Is the voltage greater than 1.5 V? 
  32. H32: CHECK FOR OVER VOLTAGE IN THE PCM 
    • Key in OFF position.
    • HO2S connector disconnected.
    • Key ON, engine OFF.
    • Measure the voltage between:
      (+) HO2S Connector, Harness Side (-) Vehicle Battery
      SIGRTN Negative terminal
      HO2S Signal Negative terminal
    • Are the voltages less than 1.5 V? 
  33. H33: CHECK FOR CORRECT PCM OPERATION 
    • Disconnect all the PCM connectors.
    • Visually inspect for:
      • pushed out pins
      • corrosion
    • Connect all the PCM connectors and make sure they seat correctly.
    • Carry out the PCM self-test and verify the concern is still present.
    • Is the concern still present? 
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