O2 Sensor Positive Current Control Circuit Low Bank 1 Sensor 1
The P2238 code indicates that the Engine Control Module (ECM) has detected a low voltage or current condition in the positive current control circuit of the oxygen sensor located before the catalytic converter on Bank 1. This circuit is responsible for regulating the sensor's heater and internal pump current. A low signal suggests a short to ground, open circuit, or a failing sensor, which can lead to inaccurate air-fuel ratio readings and reduced fuel efficiency.
01. Most Common Causes
- Faulty oxygen sensor (Bank 1 Sensor 1)
- Open or shorted wiring in the sensor circuit
- Corroded or damaged connector
- Blown fuse for the oxygen sensor heater circuit
- ECM failure (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 an OBD2 scanner to confirm the code and check for additional codes.
Step 2: Visually inspect the oxygen sensor wiring and connector for damage, corrosion, or loose connections.
Step 3: Test the sensor's heater circuit voltage and resistance with a multimeter.
Step 4: Check the relevant fuse for the oxygen sensor heater circuit.
Step 5: If wiring and fuses are okay, replace the oxygen sensor (Bank 1 Sensor 1).
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 a DIY sensor replacement, or $150-$300 at a shop including labor.