O2 Sensor Positive Current Control Circuit/Open Bank 2 Sensor 1
Code P2240 indicates an open or malfunction in the positive current control circuit of the oxygen sensor located upstream (Sensor 1) on Bank 2 (the side of the engine opposite cylinder #1). This circuit is responsible for regulating the heater current to quickly bring the sensor to operating temperature. An open circuit prevents the sensor from heating properly, leading to inaccurate air-fuel ratio readings and potential drivability issues.
1. Most Common Causes
- Faulty or aged oxygen sensor (Bank 2, Sensor 1)
- Open circuit in the positive current reference wiring
- Loose, corroded, or bent pins in the sensor harness connector
- Blown oxygen sensor heater fuse
- Short to ground in the control circuit
- Internal failure in the powertrain control module (PCM)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Poor fuel economy
- Rough idle or hesitation during acceleration
- Failed emissions test
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm code P2240 and check for additional codes.
Step 2: Visually inspect the O2 sensor wiring and connector for damage, corrosion, or loose connections.
Step 3: Measure resistance across the heater circuit pins of the sensor; compare to manufacturer specs (typically 2-10 ohms).
Step 4: Check for battery voltage and ground at the sensor connector with the ignition on; repair open circuits as needed.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
You can drive short distances, but the vehicle may run rich, reducing fuel economy and potentially damaging the catalytic converter over time. It's best to diagnose and repair promptly.
How much does it cost to fix?▼
Typically $50-$150 for a DIY replacement of the oxygen sensor, or $150-$300 if professionally installed, including parts and labor.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.