O2 Sensor Heater Control Circuit Malfunction (Bank 2 Sensor 1)
The P0050 code indicates a problem with the heater control circuit for the oxygen sensor located before the catalytic converter on bank 2 (the side of the engine not containing cylinder #1). The heater element is essential for the sensor to reach operating temperature quickly, especially during cold starts. When the Powertrain Control Module (PCM) detects an open, short, or excessive resistance in the heater circuit, it sets this code. Common causes include a faulty oxygen sensor, damaged wiring or connectors, a blown fuse, or a defective PCM relay.
01. Most Common Causes
- Faulty oxygen sensor (Bank 2 Sensor 1)
- Open or shorted heater circuit wiring or connector
- Blown fuse or bad relay for O2 sensor heater
- Corroded or damaged electrical terminals
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Increased fuel consumption
- Failed emissions test
- Rough idle or hesitation during cold start
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm P0050 and check for other codes.
Step 2: Visually inspect the O2 sensor wiring and connector for damage, corrosion, or loose connections.
Step 3: Test the heater circuit resistance at the sensor connector (should be 2-30 ohms).
Step 4: Check for battery voltage and ground at the heater circuit with the ignition on.
Step 5: If voltage and ground are present but resistance is out of spec, replace the O2 sensor.
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.