P013E: O2 Sensor Delayed Response - Rich to Lean Bank 1 Sensor 2

What it means

Post-cat O2 sensor on bank 1 reacts only after delay when mixture switches rich to lean. A drifted or sluggish lambda sensor lets the mixture run lean or rich without correction — fuel economy and emissions suffer immediately.

At a glance

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

How it works

Bank 1 Sensor 2 is the post-catalyst oxygen sensor on the first bank. P013E sets when the control module detects a delay before this sensor responds to an exhaust transition from rich to lean.

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 identify the conditions when the rich-to-lean delay was recorded.
2. Inspect Bank 1 Sensor 2, its connector, and exhaust-routed wiring for heat damage, corrosion, loose pins, or contamination.
3. Check for an exhaust leak near the downstream sensor and evidence of oil, coolant, or fuel contamination.
4. Graph Bank 1 Sensor 2 live data during a warm-engine drive or supported monitor test and look for delayed response to a rich-to-lean transition.
5. Test the signal and heater circuits and compare the sensor's timing with the manufacturer's specification.

Common fixes

• Repair damaged wiring or connector contacts at Bank 1 Sensor 2.
• Repair an exhaust leak near the post-catalyst sensor.
• Correct a confirmed source of oil, coolant, or fuel contamination.
• Replace Bank 1 Sensor 2 if its circuits are sound and the rich-to-lean delay remains.

Can I keep driving?

The vehicle may drive normally, but emissions monitoring can be incomplete and an emissions test may fail. If the engine runs rough or the check-engine light flashes, stop driving and address it promptly.