O2 Sensor Delayed Response - Rich to Lean (Bank 2 Sensor 1)
The P015C code indicates that the oxygen sensor (O2) in Bank 2, Sensor 1 is responding too slowly when switching from a rich to a lean fuel mixture. This sensor is located upstream of the catalytic converter and monitors exhaust oxygen levels to help the engine control module (ECM) adjust fuel trim. A delayed response can be caused by a contaminated or aging sensor, exhaust leaks, fuel system issues, or wiring problems. This condition can lead to incorrect air-fuel ratio adjustments, reduced fuel economy, and increased emissions.
01. Most Common Causes
- Faulty or contaminated oxygen sensor
- Exhaust leak before the sensor
- Fuel system issues (e.g., rich condition, fuel pressure)
- Wiring or connector problems in the sensor circuit
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: Inspect O2 sensor wiring and connector for damage or corrosion.
Step 3: Check for exhaust leaks upstream of the sensor.
Step 4: Monitor O2 sensor voltage with a scan tool; it should switch rapidly between 0.1V and 0.9V.
Step 5: If sensor response is slow, replace the O2 sensor (Bank 2 Sensor 1).
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, but it may cause reduced fuel economy and increased emissions. Prolonged driving could damage the catalytic converter.
How much does it cost to fix?▼
Typically $50-$150 for the sensor plus labor, which can range from $100-$200 depending on the vehicle.