O2 Sensor Delayed Response Lean to Rich Bank 2 Sensor 1
The P015D code indicates that the oxygen sensor (O2S) in Bank 2, Sensor 1 (upstream of the catalytic converter) is responding too slowly when switching from a lean to rich fuel mixture. This delayed response can be caused by a contaminated or aging sensor, exhaust leaks, fuel system issues, or wiring problems. The ECM monitors the sensor's voltage transition time; if it exceeds a threshold, the code sets.
01. Most Common Causes
- Faulty oxygen sensor (Bank 2 Sensor 1)
- Exhaust leak before the sensor
- Fuel pressure or injector issues
- Engine vacuum leak
- Wiring or connector damage to the sensor
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: Scan for codes and record freeze frame data.
Step 2: Visually inspect O2 sensor wiring and connector for damage.
Step 3: Check for exhaust leaks upstream of the sensor.
Step 4: Use a scan tool to monitor O2 sensor voltage and response time.
Step 5: If sensor fails response test, replace Bank 2 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 potential damage to the catalytic converter over time. It's best to diagnose and repair promptly.
How much does it cost to fix?▼
The cost typically ranges from $150 to $400, including parts (O2 sensor) and labor. DIY replacement can be cheaper, around $50-$150 for the sensor alone.