P0141 — Oxygen sensor heater circuit — bank 1, sensor 2

P0141 identifies a fault in the heater circuit of the downstream oxygen sensor on bank 1, sensor 2 (B1S2). The heater brings the sensor to operating temperature; the code does not by itself prove that its oxygen-sensing element has failed or that the catalytic converter requires replacement. Heater-current, resistance and control monitoring vary by vehicle.

Affected system: Oxygen sensor heating

Symptoms

• Check-engine light; often little or no noticeable running change.
• B1S2 heater readiness or test status may be incomplete or failed where the scan tool exposes it.
• Emissions may increase until the sensor warms up; rough running and high consumption are not mandatory symptoms.

Possible causes

• Open heater element or heater resistance outside the vehicle-specific specification.
• Heater fuse, supply or ground/control failure where fitted.
• Melted exhaust-side wiring, corroded connector, intermittent contact, open or shorted loom.
• ECU heater-driver fault only after heater, supply and wiring have been isolated.

What to check

• 1. Save P0141, companion codes, freeze-frame data and heater monitor status; other heater codes may point to a shared supply fault.
• 2. Identify bank 1 (the cylinder-1 bank) and B1S2 downstream of the catalyst from the engine diagram. Do not confuse it with the upstream B1S1.
• 3. With exhaust and engine cold, inspect the B1S2 wiring and connector for heat damage, snagging, water ingress and loose/corroded terminals.
• 4. Consult the heater wiring diagram and check the fuse, supply and ground/control under the OEM enable conditions. Never assume constant 12 V or a particular ground-switched strategy.
• 5. With the circuit safely isolated as specified, measure heater resistance and compare it with the exact sensor and temperature limits; an open circuit points to a heater or connection fault.
• 6. If heater resistance is in range, test the harness for opens and shorts from sensor to ECU using the specified module-disconnection safeguards.
• 7. Where supported, examine commanded heater operation and current under test conditions; command without current suggests an open path, while missing supply calls for fuse/control diagnosis.
• 8. Repair the proven connector or wiring issue, or replace the sensor only after heater failure is demonstrated. Repeat the OEM monitor and confirm P0141 does not recur. Avoid hot exhaust parts and unsupported vehicles.

Also written as: P0141-00, P014100, PO141 (some scan tools add the fault-type byte, e.g. -00).