O2 Sensor Positive Current Control Circuit Low Bank 1 Sensor 1
The P2238 code indicates that the powertrain control module (PCM) has detected a low voltage or current condition in the positive current control circuit of the oxygen sensor located in Bank 1, Sensor 1 (upstream of the catalytic converter). This circuit is responsible for regulating the sensor's heater and pump current. A low signal can result from a faulty oxygen sensor, damaged wiring or connectors, a blown fuse, or a PCM issue. This condition can lead to incorrect air-fuel ratio readings, affecting engine performance and emissions.
1. Most Common Causes
- Faulty wideband oxygen (A/F) sensor (internal open circuit in the pump cell)
- Ip+ circuit wiring shorted to ground
- Ip+ circuit wiring open (broken wire or disconnected connector)
- Sensor connector corroded, loose, or with damaged terminals
- Internal PCM sensor driver failure (rare)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Poor fuel economy
- Rough idle or hesitation
- Failed emissions test
3. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for additional codes.
Step 2: Visually inspect the O2 sensor wiring and connector for damage, corrosion, or loose connections.
Step 3: Test the O2 sensor heater circuit voltage and resistance with a multimeter.
Step 4: Check the relevant fuse and relay for the O2 sensor circuit.
Step 5: If all else is fine, replace the O2 sensor (Bank 1, 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 $50-$150 for a DIY replacement of the oxygen sensor. Labor costs at a shop can add $50-$100.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.