O2 Sensor Reference Voltage Circuit Open Bank 1 Sensor 1
The P2243 code indicates an open circuit in the reference voltage supply to the upstream oxygen sensor (Bank 1, Sensor 1). The oxygen sensor requires a stable reference voltage (typically 0.45V) from the ECU to function correctly. An open circuit means the sensor is not receiving this voltage, causing the ECU to detect a fault. This can lead to incorrect air-fuel ratio readings and affect engine performance.
01. Most Common Causes
- Open or broken wire in the oxygen sensor reference voltage circuit
- Corroded or damaged connector at the oxygen sensor
- Faulty oxygen sensor
- Blown fuse related to the oxygen sensor circuit
- ECU internal fault (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Poor fuel economy
- Rough idle or hesitation
- Failed emissions test
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm the code and check for other related codes.
Step 2: Visually inspect the wiring and connector for Bank 1 Sensor 1 for damage, corrosion, or loose connections.
Step 3: With the key on, engine off, measure voltage at the sensor connector reference voltage pin (should be around 0.45V). If 0V, check for open circuit back to ECU.
Step 4: Check continuity of the reference voltage wire from sensor to ECU. Repair or replace as needed.
Step 5: If wiring is intact, replace the oxygen sensor.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
You can drive short distances, but it may cause poor fuel economy and increased emissions. Prolonged driving could damage the catalytic converter.
How much does it cost to fix?▼
Typically $50-$150 for diagnosis and repair, including parts and labor. Sensor replacement costs around $50-$100, plus labor.