P013C: O2 Sensor Slow Response - Rich to Lean Bank 2 Sensor 2

What it means

Post-cat O2 sensor on bank 2 responds too slowly when mixture transitions from rich to lean. Sensor aging or contamination.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

Bank 2 Sensor 2 is the oxygen sensor after the catalytic converter on the engine's second bank. P013C sets when the control module detects that this downstream sensor responds too slowly during a rich-to-lean exhaust transition.

Common causes

Most likely first.

1. Oxygen sensor aged or sluggish
2. Sensor contaminated by oil, coolant, or fuel
3. Exhaust leak near the sensor
4. Sensor wiring or connector fault

Symptoms

• Check engine light on
• Failed emissions test

How to diagnose it

1. Review freeze-frame data and monitor status to confirm when the Bank 2 rich-to-lean response test failed.
2. Locate Bank 2 Sensor 2 using the vehicle information, then inspect its sensor body, connector, and exhaust-routed harness for damage or corrosion.
3. Check for an exhaust leak near the Bank 2 catalyst outlet and look for oil, coolant, or fuel contamination.
4. Graph Bank 2 Sensor 2 live data during a warm-engine drive or supported monitor test and observe its response to a rich-to-lean transition.
5. Test the Bank 2 Sensor 2 signal and heater circuits and compare response with the manufacturer's specification.

Common fixes

• Repair damaged wiring or connector contacts at Bank 2 Sensor 2.
• Repair an exhaust leak near the Bank 2 downstream sensor.
• Resolve any confirmed oil, coolant, or fuel contamination source.
• Replace Bank 2 Sensor 2 if it remains slow after the wiring and exhaust checks.

Can I keep driving?

The engine may run normally, but the catalyst monitor may not complete and the vehicle may fail an emissions test. Arrange diagnosis soon, and stop driving if the engine runs poorly or the check-engine light flashes.