Aged or contaminated downstream oxygen sensor (sensor 2) that has become slow to respond; Exhaust leaks upstream of the sensor, allowing outside air to affect the reading; Wiring damage or corrosion in the sensor circuit, including the signal, ground, or heater wires; A failing catalytic converter that is not storing oxygen properly, altering the sensor's switching behavior; Engine misfires or rich running conditions that have fouled the sensor over time; Use of leaded fuel or silicone-based sealants that poison the sensor element

DTC codes / P01xx · Fuel and air metering / P013E

P013EO2 Sensor Delayed Response - Rich to Lean Bank 1 Sensor 2

Q: What does code P013E mean?

O2 Sensor Delayed Response - Rich to Lean Bank 1 Sensor 2. P013E means the powertrain control module (PCM) has detected that the downstream oxygen sensor on bank 1, which is sensor 2 after the catalytic converter, is taking too long to switch from a rich to a lean signal. The PCM monitors the sensor's voltage transitions and sets this code when the rich-to-lean response time exceeds the calibrated limit, indicating a lazy or contaminated sensor or a wiring issue.

P013E means the powertrain control module (PCM) has detected that the downstream oxygen sensor on bank 1, which is sensor 2 after the catalytic converter, is taking too long to switch from a rich to a lean signal. The PCM monitors the sensor's voltage transitions and sets this code when the rich-to-lean response time exceeds the calibrated limit, indicating a lazy or contaminated sensor or a wiring issue.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Symptoms you may notice

Illumination of the check engine light, often with no other symptoms noticed by the driver
A slight decrease in fuel economy as the PCM may default to a richer fuel mixture
Occasional rough idle or hesitation during acceleration if the sensor response is severely delayed
Failed emissions test due to increased hydrocarbon or carbon monoxide levels
In rare cases, a sulfur or rotten egg smell from the exhaust if the rich condition persists

Common causes, most likely first

Aged or contaminated downstream oxygen sensor (sensor 2) that has become slow to respond
Exhaust leaks upstream of the sensor, allowing outside air to affect the reading
Wiring damage or corrosion in the sensor circuit, including the signal, ground, or heater wires
A failing catalytic converter that is not storing oxygen properly, altering the sensor's switching behavior
Engine misfires or rich running conditions that have fouled the sensor over time
Use of leaded fuel or silicone-based sealants that poison the sensor element

How to diagnose and fix it

Perform a visual inspection of the downstream oxygen sensor and its wiring for damage, corrosion, or loose connections
Check for exhaust leaks between the engine and the sensor using a smoke machine or by listening for ticking sounds
Use a scan tool to view live data for the downstream oxygen sensor and compare its switching rate to the upstream sensor
Test the sensor's heater circuit resistance and supply voltage to rule out a heater fault
Replace the downstream oxygen sensor if it is slow or unresponsive, using the correct OEM or equivalent part
Clear the diagnostic trouble codes and perform a drive cycle to verify the repair
If the code returns, inspect the catalytic converter for efficiency and replace if necessary

Downstream sensor myths and misdiagnosis traps

A slow downstream oxygen sensor does not always mean the sensor is bad; exhaust leaks before the sensor can cause false lean readings and delayed switching.
Many technicians replace the catalytic converter prematurely when the real culprit is a contaminated or aged sensor that is simply slow to respond.
The downstream sensor's switching rate is influenced by the catalytic converter's oxygen storage capacity, so a failing converter can mimic a sensor fault.
Wiring issues such as a chafed signal wire or a poor ground can cause intermittent delayed response that may not appear during a quick test drive.
Using the wrong type of silicone sealant on exhaust components can poison the oxygen sensor and lead to this code even on a relatively new sensor.

Can I keep driving with P013E?

You can generally continue driving with P013E, but avoid aggressive acceleration and heavy loads until the fault is repaired. Prolonged driving with a delayed sensor can increase emissions and may eventually damage the catalytic converter, so schedule diagnosis soon.

Tools that help

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