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 1533 (ENGINE CONTROLS - POWERTRAIN DTC CHARTS & DESCRIPTIONS - DTC P164B THROUGH DTC UXXXX - (EXCEPT DIESEL & HYBRID))DTC P2195: O2 SENSOR SIGNAL BIASED/STUCK LEAN - BANK 1, SENSOR 1

2010 Mercury Mariner Hybrid, AWD

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

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

WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2011 Mercury Milan, 2011 Mercury Mariner, 2011 Mercury Grand Marquis, 2011 Lincoln Town Car, and 2011 Lincoln Navigator L. 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 voltage in the harness or HO2S Water in the harness connector Open HO2S circuit Open UO2SPC circuit Corrosion Incorrect harness connections Damaged HO2S Damaged powertrain control module (PCM) Fuel System: Excessive fuel pressure Leaking or contaminated fuel injectors Leaking fuel pressure regulator Low fuel pressure or running out of fuel Evaporative Emission (EVAP) System: EVAP canister purge (EVAPCP) valve stuck open Intake Air System: Air leaks after the mass airflow (MAF) sensor Vacuum leaks Positive crankcase ventilation (PCV) system is leaking or the valve is stuck open Incorrectly seated engine oil dipstick Exhaust Gas Recirculation (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
Diagnostic Aids:
Application	Key On Engine Off	Key On Engine Running	Continuous Memory
All	GO 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.