O2 Sensor Reference Voltage Circuit/Open Bank 1 Sensor 1
P2243 indicates the PCM detected a voltage reference circuit problem or open circuit condition in the oxygen sensor circuit on Bank 1, Sensor 1. This sensor is critical for proper air-fuel ratio control and emissions management. The code typically means the PCM cannot establish proper reference voltage communication with the upstream oxygen sensor.
What You Might Notice
- Check Engine Light illuminated
- Reduced fuel economy
- Rough idle or hesitation during acceleration
- Stored lean or rich mixture codes
- Diminished engine performance
Most Common Causes
- 1
Open or damaged O2 sensor wiring
Broken, corroded, or disconnected wiring harness to the Bank 1 Sensor 1 oxygen sensor disrupts voltage signal transmission to the PCM.
- 2
Faulty oxygen sensor
The oxygen sensor itself has failed internally and cannot generate proper voltage signals or respond to reference voltage from the PCM.
- 3
Blown O2 sensor fuse or relay
A blown fuse or failed relay in the oxygen sensor circuit prevents proper power and reference voltage from reaching the sensor.
- 4
PCM connector or reference voltage supply issue
Corroded PCM connectors, loose connections, or a failing reference voltage output from the PCM prevents proper sensor communication.
How to Diagnose It
- 1
Check Open or damaged O2 sensor wiring — Broken, corroded, or disconnected wiring harness to the Bank 1 Sensor 1 oxygen sensor disrupts voltage signal transmission to the PCM.
- 2
Check Faulty oxygen sensor — The oxygen sensor itself has failed internally and cannot generate proper voltage signals or respond to reference voltage from the PCM.
- 3
Check Blown O2 sensor fuse or relay — A blown fuse or failed relay in the oxygen sensor circuit prevents proper power and reference voltage from reaching the sensor.
- 4
Check PCM connector or reference voltage supply issue — Corroded PCM connectors, loose connections, or a failing reference voltage output from the PCM prevents proper sensor communication.
How to Fix It
- 1
Inspect and repair O2 sensor wiring
Visually inspect the oxygen sensor wiring harness from the sensor to the PCM for damage, corrosion, or loose connections. Repair or replace damaged wiring and reconnect any loose terminals.
- 2
Replace oxygen sensor
Remove the faulty Bank 1 Sensor 1 oxygen sensor using an O2 sensor socket and install a new OEM or quality aftermarket oxygen sensor. Apply anti-seize compound to the threads.
- 3
Check and replace O2 sensor fuse
Locate the oxygen sensor fuse in the main fuse box or engine bay, inspect for blown condition, and replace with the correct amperage rating if needed.
- 4
Inspect PCM connectors and reference voltage
Clean corrosion from PCM connectors, check connector fit and terminal conditions, and use a multimeter to verify proper reference voltage output from the PCM to the oxygen sensor circuit.
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