Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSMERCURY2010MARINER HYBRID, AWDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 865 (ENGINE CONTROLS - POWERTRAIN DTC CHARTS AND DESCRIPTIONS - (HYBRID))DTC DIAGNOSISP2195 - O2 SENSOR SIGNAL BIASED/STUCK LEAN - BANK 1, SENSOR 1

2010 Mercury Mariner Hybrid, AWD

P2195 - O2 Sensor Signal Biased/Stuck Lean - Bank 1, Sensor 1

2010 Mercury Mariner Hybrid, AWDSECTION P2195 - O2 Sensor Signal Biased/Stuck Lean - Bank 1, Sensor 1

WARNING: This page is about a different car, the 2007 Mercury Mariner and 2007 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.

P2195 - O2 SENSOR SIGNAL BIASED/STUCK LEAN - BANK 1, SENSOR 1

Description:	A heated oxygen sensor (HO2S) indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when the fuel control system no longer detects switching for a calibrated amount of time.
Possible Causes:	Electrical: Short to VPWR in the harness or HO2S Water in the harness connector Open/shorted HO2S circuit Corrosion or poor mating terminals and wiring Damaged HO2S Fuel System: Excessive fuel pressure Leaking/contaminated fuel injectors Leaking fuel pressure regulator Low fuel pressure or running out of fuel Vapor recovery system Intake Air System: Air leaks after the mass air flow (MAF) sensor Vacuum leaks Positive crankcase ventilation (PCV) system Improperly seated engine oil dipstick EGR System: Leaking gasket Stuck EGR valve Leaking diaphragm or EGR vacuum regulator Base Engine: Oil overfill Camshaft timing Cylinder compression Exhaust leaks before or near the HO2S(s)
Diagnostic Aids:
Application		Key On Engine Off	Key On Engine Running	Continuous Memory
All		refer to PINPOINT TEST H .

RENDER: 1.0x

NO RELATED

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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.