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HOMESERVICE MANUALSMERCURY2010MARINER HYBRID, AWDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 269 (EXHAUST SYSTEM)DIAGNOSIS AND TESTINGEXHAUST SYSTEMPINPOINT TESTPINPOINT TEST A: RESTRICTED EXHAUST SYSTEM TEST
2010 Mercury Mariner Hybrid, AWD

Pinpoint Test A: Restricted Exhaust System Test

2010 Mercury Mariner Hybrid, AWDSECTION Pinpoint Test A: Restricted Exhaust System Test
WARNING: This page is about a different car, the 2006 Mercury Grand Marquis and 2006 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.
  1. A1 EXHAUST SYSTEM INSPECTION 
      WARNING: If equipped with fire suppression system, depower the system. For important safety warnings and procedures, refer to FIRE SUPPRESSION SYSTEM .
    • With the vehicle in NEUTRAL, position it on a hoist. For additional information, refer to JACKING & LIFTING .
    • Inspect the exhaust system for damage or deterioration. Look for cracks, punctures, leaks, loose connections, dents or unusual bending.
    • Is the exhaust system OK? 

    Yes  : GO to A2.

    No  : REPAIR or INSTALL any damaged or deteriorated exhaust components. Test the system for normal operation. If equipped with fire suppression system, GO to  A4.

  2. A2 BACK PRESSURE TEST 
    • Connect a tachometer.
    • Using the special tool, remove the upstream heated oxygen sensor (HO2S).
    • Install the back pressure gauge.
    • Start the engine and gradually increase the engine speed to 2,000 rpm with the transmission in NEUTRAL.
    • Is the back pressure greater than 27.6 kPa (4 psi)? 

    Yes  : GO to A3.

    No  : No indications of a restriction have been detected. CONDUCT a diagnosis on other suspect systems. CLEAR the DTCs. If equipped with fire suppression system, GO to  A4.

  3. A3 BACK PRESSURE TEST - CATALYTIC CONVERTER(S) ON, MUFFLER(S) OFF 
    • Turn the engine OFF.
    • Disconnect the muffler assembly from the catalytic converter.
    • Repeat the back pressure test.
    • Is the back pressure greater than 27 kPa (4 psi)? 

    Yes  : The restriction is in the catalytic converter. INSTALL a new catalytic converter. INSPECT the muffler to be sure the catalytic converter foreign material has not entered the muffler. CLEAR the DTCs. TEST the system for normal operation. If equipped with fire suppression system, GO to A4.

    No  : The restriction is in the muffler assembly. INSTALL a new muffler. CLEAR the DTCs. TEST the system for normal operation. If equipped with fire suppression system, GO to A4.

  4. A4 REPOWER THE FIRE SUPPRESSION SYSTEM 
      WARNING: If equipped with fire suppression system, depower the system. For important safety warnings and procedures, refer to FIRE SUPPRESSION SYSTEM .
    • Verify that the fire suppression system is repowered. For additional information, refer to FIRE SUPPRESSION SYSTEM .
    • Is the fire suppression system repowered? 

    Yes  : Fire suppression system repowering is complete.

    No  : Refer to FIRE SUPPRESSION SYSTEM for fire suppression system depowering and repowering procedure.

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.