LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Hyundai >> 2003 >> Santa Fe Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 2.4L >> Diagnostic Tests >> DTC P0134: Ho2S Sensor Circuit No Activity Detected Bank 1/Sensor 1 >> Inspection/Repair >> System Inspection
April 5, 2026: LEMON Manuals is launched! Read the announcement.

System Inspection

  1. Check Air Leakage.
    1. Visually/physically inspect the air leakage in intake/exhaust system as following items.
      1. If OK, go to " 2 Check for air leakage in EVAP purge control valve" as below.
      2. If NG, repair as necessary and go to "VERIFICATION OF VEHICLE REPAIR " procedure.
      1. Vacuum hoses for splits, kinks and improper connections.
      2. Throttle body gasket.
      3. Gasket between intake manifold and cylinder head.
      4. Seals between intake manifold and fuel injectors.
      5. Exhaust system between HO2S and Three way catalyst for air leakage.
    2. Check for air leakage in EVAP purge control valve.
      1. With engine idling disconnect hose from EVAP purge valve side of hose.
      2. Check no vacuum at EVAP purge solenoid valve.
      3. Is vacuum available at purge valve when EVAP purge valve is not in operating?

        YES

        1. Repair or replace as necessary and go to "VERIFICATION OF VEHICLE REPAIR " procedure.

        NO

        1. Go to " 3 Check for air leakage in Positive Crankcase Ventilation Valve (PCV)" as below.
    3. Check for air leakage in Positive Crankcase Ventilation Valve (PCV).
      1. Remove PCV valve from cylinder head cover by pulling ventilation hose.
      2. With engine idling block PCV valve opening.
      3. Confirm that vacuum is felt.
      4. Remove PCV valve.
      5. Blow through valve from port "A" and verify that air comes out of port "B".
      6. Blow through valve from port "B" and verify that no air comes out of port "A".
      7. Has a problem been found?

        YES

        1. Repair or replace as necessary and go to "VERIFICATION OF VEHICLE REPAIR " procedure.

        NO

        1. Go to " 2 Check Fuel System" as below.
  2. Fuel System.
    1. Fuel Pump Test.
      1. Connect Scantool & Ignition "ON".
      2. Perform Actuation Test for Fuel Pump with scantool.
      3. Check that Fuel Pump operating sound can be heard.
        Fig 1: Display Actuation Test For Fuel Pump On Scantool
        G07823323
      4. Does the Fuel Pump operates correctly?

        YES

        1. Go to " 3 Fuel Pressure Test" as below.

        NO

        1. Substitute with a known - good Fuel Pump and check for proper operation.

          If the problem is corrected, replace HO2S and go to "VERIFICATION OF VEHICLE REPAIR " procedure.

  3. Fuel Pressure Test.
    NOTE:
    1. Be cautious that Fuel is explosive and an empty fuel tank can still contain explosive gases. When working on fuel system make sure to supply adequate ventilation to the work area. Do not smoke, and keep sparks and open flames away.
    2. The fuel system remains under pressure when the engine is not running. Release fuel system pressure before disconnecting any fuel line to reduce the chance of personal injury or fire damage to vehicle components.
    1. Check the fuel for excessive water, alcohol, or other contaminants. Replace contaminated fuel as necessary.
    2. Install the fuel pressure gauge to the fuel pressure gauge adaptor.
    3. Apply battery voltage to the terminal for the pump drive and activate the fuel pump: then, with fuel pressure applied, check that there is no fuel leakage from the pressure gauge or connection part.
    4. Disconnect the vacuum hose from the pressure regulator, and plug the hose end. Measure the fuel pressure at idle.
      1. Specification: 320~340 kPa (3.26~3.47 kg/cm2 , 46~49 psi)
    5. Measure the fuel pressure when the vacuum hose is connected to the pressure regulator.
      1. Specification: Approx. 255 kPa (2.57 kg/cm2 , 37 psi)
    6. Are the measured fuel pressure within specifications?

      YES

      1. Go to " 4 Check injector leakage" as below.

      NO

      1. Repair or replace according to the below table. And then, go to "VERIFICATION OF VEHICLE REPAIR " procedure.
        FUEL PRESSURE SYMPTOM CHART

        Condition Possible Cause
        Fuel Pressure is too low Fuel filter, fuel pressure regulator, in-tank fuel hose or the fuel pump
        Fuel Pressure is too high Fuel pressure regulator, hose or pipe
        No different fuel pressure when vacuum hose is connected or not The vacuum hose or the nipple
  4. Check Injector Leakage.
    1. Ignition "OFF" after checking the Fuel Pressure Test.
    2. Stop the engine and check for a change in the fuel pressure gauge reading for 5 minutes.
    3. Does fuel pressure drop after engine is stopped?

      YES

      1. Go to "COMPONENT INSPECTION " procedure.

      NO

      1. Repair or replace according to the below table. And then, go to "VERIFICATION OF VEHICLE REPAIR " procedure.
        FUEL PRESSURE SYMPTOM CHART

        Condition Possible Cause
        Fuel Pressure reading drops slowly after engine is stopped Injector leakage
        Fuel Pressure reading drops immediately after engine is stopped Fuel pump
scientia non olet · About LEMON Manuals