P013D
O2 Sensor Slow Response - Lean to Rich (Bank 2 Sensor 2)P013D is a generic OBD-II powertrain diagnostic trouble code: O2 Sensor Slow Response - Lean to Rich (Bank 2 Sensor 2). It is logged by the engine control unit when the o2/lambda monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P013D means
P013D is set when the PCM determines that the downstream oxygen sensor on Bank 2 (the engine bank not containing cylinder 1) — specifically Sensor 2, located after the catalytic converter — is responding too slowly when transitioning from a lean exhaust mixture to a rich exhaust mixture. A healthy downstream O2 sensor should switch its output voltage from low (approximately 0.1 V, indicating lean/high oxygen) to high (approximately 0.9 V, indicating rich/low oxygen) within a defined timeframe, typically under one second. When the PCM measures that the lean-to-rich voltage transition is taking longer than the calibrated threshold across multiple test cycles, it logs P013D. This downstream sensor primarily monitors catalytic converter efficiency rather than actively trimming fuel, but a sluggish response can indicate a worn, poisoned, or heat-damaged sensor that is no longer accurately reflecting post-cat exhaust composition. It can also point to an exhaust leak upstream of the sensor diluting the signal, or a degraded catalyst that is itself altering exhaust chemistry and masking the expected lean-to-rich swing.
Common causes
Most-frequently reported root causes when P013D is logged.
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1
Worn or aged downstream oxygen sensor with a degraded zirconium dioxide element
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2
Sensor contamination from oil consumption, coolant leak into combustion, or silicone-based sealants
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3
Exhaust leak upstream of the Bank 2 Sensor 2 location introducing extra oxygen and distorting readings
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4
Degraded catalytic converter on Bank 2 that alters post-cat exhaust chemistry
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5
Damaged, heat-burned, or open sensor wiring and connector near the exhaust system
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6
Persistent rich fuel trim on Bank 2 caused by injector or fuel pressure issues that mask the lean-to-rich transition speed
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7
Engine oil burning causing phosphorus/sulphur poisoning of the sensor element
Symptoms drivers notice
How to diagnose P013D
A typical diagnostic flow when this code is present.
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1
Connect an OBD-II scanner and record all DTCs and freeze frame data; note if P0430 (catalyst efficiency Bank 2) or fuel trim codes are present alongside P013D
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2
Clear codes and perform a warm drive cycle; use the scanner's O2 sensor data stream to monitor Bank 2 Sensor 2 voltage and confirm the lean-to-rich switching speed is genuinely slow rather than a one-off event
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3
Visually inspect the Sensor 2 wiring harness and connector for heat damage, chafing against exhaust components, or corrosion
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4
Check for exhaust leaks between the Bank 2 catalytic converter and the Sensor 2 bung using a smoke machine or by listening/feeling for exhaust gas escape
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5
Inspect for signs of oil or coolant consumption (blue or white exhaust smoke, fouled spark plugs) that could be poisoning the sensor
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6
If the sensor response remains slow with no exhaust leaks or wiring faults found, replace the Bank 2 Sensor 2 downstream O2 sensor
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7
After replacing the sensor, perform a complete drive cycle and confirm the lean-to-rich switching time meets PCM thresholds before closing the repair
Related powertrain codes
- P0040 — Upstream Oxygen Sensors Swapped From Bank To Bank
- P0041 — Downstream Oxygen Sensors Swapped From Bank To Bank
- P0130 — O2 Sensor Circuit Malfunction (Bank 1 Sensor 1)
- P0131 — O2 Sensor Circuit Low Voltage (Bank 1 Sensor I)
- P0132 — O2 Sensor Circuit High Voltage (Bank 1 Sensor 1)
- P0133 — O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)
Frequently asked questions
Will P013D cause my car to fail an emissions test?
Yes, in most regions. P013D illuminates the MIL and triggers an incomplete or failed OBD readiness monitor for the catalyst system. A lit MIL alone is grounds for an emissions failure in most jurisdictions regardless of tailpipe output.
What is the difference between P013B and P013D?
P013B is the lean-to-rich slow response code for Bank 1 Sensor 2 (the bank containing cylinder 1). P013D is the identical fault on Bank 2 Sensor 2 (the opposite bank). The root causes and diagnostic procedure are the same; only the physical sensor location differs.
Can a bad catalytic converter cause P013D without a faulty sensor?
Yes. A severely degraded catalyst on Bank 2 stores and releases oxygen in an abnormal pattern, which can make a perfectly functional downstream sensor appear to switch slowly because the exhaust chemistry it is measuring is itself abnormal.
How long does an oxygen sensor typically last before needing replacement?
Wideband upstream sensors typically last 60,000–100,000 miles. Downstream narrowband sensors often last longer but are more susceptible to catalyst-related contamination. On high-mileage vehicles showing P013D, sensor replacement is usually the correct first step.
Disabling P013D in software
RaceTune can permanently disable P013D — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
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