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 before the catalytic converter on Bank 2 (the side opposite cylinder #1). This circuit is responsible for regulating the sensor's heater current. An open circuit prevents the sensor from reaching operating temperature quickly, causing incorrect air-fuel ratio readings and potentially increasing emissions.
01. Most Common Causes
- Open or shorted wiring in the O2 sensor heater circuit
- Faulty O2 sensor (Bank 2 Sensor 1)
- Blown fuse or relay for the O2 sensor heater
- Corroded or damaged connector at the sensor
- ECU (Engine Control Unit) failure (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Poor fuel economy
- Rough idle or hesitation
- Failed emissions test
- Possible black smoke from exhaust (rich mixture)
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm code P2240 and check for related codes.
Step 2: Visually inspect the wiring and connector for Bank 2 Sensor 1 for damage, corrosion, or loose connections.
Step 3: Test the heater circuit resistance at the sensor connector (typically 2-10 ohms). If open, replace the sensor.
Step 4: Check the fuse and relay for the O2 sensor heater circuit; replace if blown.
Step 5: If wiring and sensor are good, test for voltage at the sensor connector with key on (should be battery voltage). If missing, repair wiring or ECU issue.
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, increased emissions, and potential damage to the catalytic converter over time. It's best to diagnose and repair promptly.
How much does it cost to fix?▼
Typically $150-$300 for parts and labor, depending on the cause. A simple sensor replacement costs around $100-$200, while wiring repairs may add $50-$100.