Open or damaged wiring in the reference voltage circuit between the PCM and the bank 2 sensor 1 oxygen sensor.; Corroded, loose, or disconnected electrical connector at the oxygen sensor or PCM.; Failed oxygen sensor with an internal open circuit on the reference voltage side.; Blown fuse that supplies power to the oxygen sensor heater circuit, which can affect reference voltage.; Faulty PCM driver for the reference voltage circuit, though this is less common.; Exhaust leaks upstream of the sensor causing erratic readings that mimic a circuit fault.; Contamination of the sensor from coolant or oil, leading to internal circuit damage.

DTC codes / P22xx · Fuel and air metering (injector circuits) / P2247

P2247O2 Sensor Reference Voltage Circuit/Open (Bank 2 Sensor 1)

Q: What does code P2247 mean?

O2 Sensor Reference Voltage Circuit/Open (Bank 2 Sensor 1). P2247 indicates that the powertrain control module (PCM) has detected an open circuit or abnormal voltage on the reference voltage circuit for the upstream oxygen sensor on bank 2, which is the side of the engine that does not contain cylinder number one. The PCM monitors this circuit to ensure the sensor receives a stable reference voltage, typically around 0.45 volts, and sets the code when the voltage falls outside the expected range for a calibrated time period.

P2247 indicates that the powertrain control module (PCM) has detected an open circuit or abnormal voltage on the reference voltage circuit for the upstream oxygen sensor on bank 2, which is the side of the engine that does not contain cylinder number one. The PCM monitors this circuit to ensure the sensor receives a stable reference voltage, typically around 0.45 volts, and sets the code when the voltage falls outside the expected range for a calibrated time period.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering (injector circuits)

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms.
Rough idle or engine stumbling, particularly when the engine is cold.
Poor fuel economy due to the PCM reverting to open-loop fuel control.
Hesitation or sluggish acceleration during normal driving.
Increased tailpipe emissions, which may cause a failed emissions test.
In rare cases, a slight sulfur or rotten egg smell from the exhaust.

Common causes, most likely first

Open or damaged wiring in the reference voltage circuit between the PCM and the bank 2 sensor 1 oxygen sensor.
Corroded, loose, or disconnected electrical connector at the oxygen sensor or PCM.
Failed oxygen sensor with an internal open circuit on the reference voltage side.
Blown fuse that supplies power to the oxygen sensor heater circuit, which can affect reference voltage.
Faulty PCM driver for the reference voltage circuit, though this is less common.
Exhaust leaks upstream of the sensor causing erratic readings that mimic a circuit fault.
Contamination of the sensor from coolant or oil, leading to internal circuit damage.

How to diagnose and fix it

Perform a visual inspection of the bank 2 sensor 1 oxygen sensor wiring and connector for damage, corrosion, or loose pins.
Check the oxygen sensor heater circuit fuse and replace if blown, as a blown fuse can interrupt reference voltage.
Use a digital multimeter to measure reference voltage at the sensor connector with the key on and engine off; compare to the manufacturer's specification.
Backprobe the reference voltage wire at the PCM connector to verify continuity and check for an open circuit between the PCM and sensor.
Inspect for exhaust leaks near the sensor using a smoke machine or by listening for ticking sounds when cold.
Replace the bank 2 sensor 1 oxygen sensor if the circuit tests good but the sensor does not produce the correct reference voltage.
Clear the diagnostic trouble codes and perform a road test to verify the repair, ensuring the code does not return.

Reference voltage faults often misdiagnosed

A common mistake is replacing the oxygen sensor immediately, but the fault is frequently in the wiring harness or connector rather than the sensor itself.
The reference voltage circuit is shared with other sensors on some vehicles, so a fault in a related sensor can cause P2247 to set even if the oxygen sensor is fine.
Exhaust leaks upstream of the sensor can introduce oxygen and cause the sensor to report a lean condition, which the PCM may interpret as a reference voltage error.
A weak battery or charging system issue can cause voltage fluctuations that trigger P2247, so always check battery health before condemning the sensor.
The code can set intermittently due to vibration or temperature changes, making it important to wiggle-test the harness while monitoring live data.

Can I keep driving with P2247?

You can generally continue driving with P2247, but avoid aggressive acceleration and heavy loads because the engine may run rich or lean, reducing fuel economy and increasing emissions. Have the fault diagnosed soon to prevent potential damage to the catalytic converter from prolonged incorrect fuel mixtures.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.