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DTC codes / P01xx · Fuel and air metering / P013D

P013DO2 Sensor Slow Response - Lean to Rich Bank 2 Sensor 2

P013D means the powertrain control module (PCM) has detected that the downstream oxygen sensor on bank 2 (the side of the engine that does not contain cylinder 1) is responding too slowly when the air-fuel mixture transitions from lean to rich. The PCM monitors the sensor's voltage switching rate and sets this code when the signal lags beyond a calibrated threshold during a lean-to-rich transition.

SystemPowertrain
Code typeGeneric (all makes)
SeverityLow
Fix difficultyIntermediate
AreaFuel and air metering

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms.
  • A slight decrease in fuel economy as the PCM may default to a richer mixture.
  • Occasional hesitation or stumble during acceleration if the slow response affects fuel trim.
  • In some cases, a faint sulfur or rotten egg smell from the exhaust due to a rich condition.
  • Rough idle or uneven running if the sensor's slow response disrupts closed-loop fuel control.
  • No drivability issues at all in many instances, especially if the sensor is only marginally slow.

Common causes, most likely first

  1. A degraded or aged oxygen sensor that has lost its responsiveness over time.
  2. Contamination of the sensor tip from oil, coolant, or silicone (from improper sealants).
  3. Exhaust leaks upstream of the sensor, allowing outside air to skew the reading.
  4. Wiring damage such as frayed, corroded, or shorted wires in the sensor circuit.
  5. A failing catalytic converter that alters the exhaust gas composition and confuses the sensor.
  6. Engine misfires or rich-running conditions that overload the sensor with unburned fuel.
  7. Use of leaded fuel or improper fuel additives that poison the sensor.

How to diagnose and fix it

  1. Use an OBD-II scanner to verify P013D is the only code and check for pending or stored related codes.
  2. Inspect the bank 2 sensor 2 wiring and connector for damage, corrosion, or loose pins.
  3. Perform a visual inspection of the exhaust system for leaks upstream of the sensor.
  4. Use a scan tool to view live data for the bank 2 sensor 2 voltage and compare its switching rate to the bank 1 sensor 2.
  5. Check fuel trims and misfire counters to rule out engine conditions that could damage the sensor.
  6. Test the sensor's heater circuit resistance and compare to manufacturer specifications.
  7. Replace the bank 2 sensor 2 with a quality direct-fit sensor if diagnostics confirm it is slow or contaminated.

Downstream Sensor Slow Response Traps

  • A slow downstream oxygen sensor often does not set a heater circuit code, so technicians who only check for heater faults may overlook it.
  • Exhaust leaks between the catalytic converter and the sensor can cause a false slow-response reading by diluting the exhaust sample.
  • The PCM may set P013D only during specific driving conditions, such as steady cruise or after a cold start, so a test drive with live data is essential.
  • Replacing the sensor without addressing an underlying rich condition or misfire will lead to repeat failure and the same code returning.
  • Bank 2 sensor 2 is often the least accessible sensor, and a faulty connector or chafed harness is a common root cause that is missed.

Can I keep driving with P013D?

You can generally continue driving with P013D, but avoid ignoring it for long because a slow sensor can gradually degrade fuel economy and increase emissions. Have the vehicle diagnosed soon to prevent potential catalytic converter damage from prolonged rich operation.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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