O2 Sensor Reference Voltage Performance Bank 2 Sensor 1
Code P2248 indicates that the oxygen sensor (Bank 2, Sensor 1) reference voltage is out of the expected range. This sensor is located before the catalytic converter on the engine bank opposite cylinder #1. The reference voltage is typically 0.45 volts when the sensor is at stoichiometric air-fuel ratio. A performance issue means the voltage is stuck, slow to respond, or outside the normal operating range, often due to a faulty sensor, wiring issues, or exhaust leaks.
1. Most Common Causes
- Faulty or degraded oxygen (O2) sensor
- O2 sensor wiring shorted to ground, to voltage, or open circuit
- Corroded, oxidized, or damaged O2 sensor connector pins
- Internal ECM/PCM failure causing incorrect reference voltage
- Abnormal electrical resistance in the O2 sensor reference circuit
- Blown fuse related to the O2 sensor circuit
- Non-factory electrical modifications affecting the reference circuit
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Poor fuel economy
- Rough idle or hesitation
- Failed emissions test
- Possible black smoke from exhaust
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect the O2 sensor wiring and connector for damage, corrosion, or loose connections.
Step 3: Use a multimeter to check the sensor's reference voltage (should be around 0.45V at idle).
Step 4: Check for exhaust leaks near the sensor using a smoke machine or soapy water.
Step 5: If wiring and exhaust are good, replace the O2 sensor (Bank 2, Sensor 1).
4. 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 $150-$350 including parts and labor. The sensor itself costs $50-$150, and labor is about $100-$200.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.