P015E
Excessive Time to Enter Closed Loop Fuel Timing Control.
- Generic
- Powertrain
- Generic code
- Low severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 1
- AreaFuel and air metering
- 5E
- FaultThe specific fault in that area
What it means
P015E is a generic powertrain code meaning the engine control unit took longer than expected to switch from open loop to closed loop fuel control after start-up. In closed loop the ECU trims fuelling using the oxygen or air-fuel ratio sensor signals. The code sets when those sensors have not become active and stable within the calibrated time, usually because of slow sensor heat-up, a sensor or heater fault, or a very low engine temperature.
Symptoms
- Malfunction indicator lamp on
- Slightly higher fuel consumption, especially on short journeys
- Rough or uneven idle for longer than usual after a cold start
- Poor cold-start driveability or hesitation
- Failed emissions test or high readings at idle
- Other oxygen sensor or coolant temperature codes stored alongside it
Possible causes
- Faulty oxygen or air-fuel ratio sensor, or a slow-responding sensor, upstream of the catalystlikely
- Sensor heater circuit fault, such as an open heater element, blown fuse or failed relaylikely
- Engine coolant temperature sensor reading wrongly or an engine that is slow to warm up, for example from a stuck-open thermostatlikely
- Damaged wiring or poor connections in the sensor signal or heater circuits, including corrosion or heat damagepossible
- Exhaust leak ahead of or near the sensor letting in air and giving misleading readingspossible
- Fuel delivery or air metering fault, or a vacuum leak, upsetting the mixture so the ECU cannot enter closed looppossible
- Outdated or faulty ECU software calibration, where the manufacturer has issued a known update for this faultrare
How to diagnose
- Read all stored and pending codes and the freeze frame data, noting coolant temperature, engine load and time since start
- Check for related codes for sensors, heaters, coolant temperature or fuelling and deal with those first
- Inspect the sensor wiring, connectors and relevant fuses and relays for damage, corrosion or heat damage
- Compare coolant temperature on live data with a known reference to check the sensor, and confirm the engine reaches normal operating temperature in a reasonable time
- Watch the oxygen or air-fuel ratio sensor live data from a cold start to see how quickly it becomes active and whether it responds to mixture changes
- Test the sensor heater circuit for supply, earth and element resistance against the manufacturer's specification, which varies by model and sensor type
- Check for exhaust leaks near the sensors and for vacuum leaks, and review short and long term fuel trims
- Check whether a software update applies to the vehicle for this code, following the manufacturer's information
How to fix
- Replace the faulty or slow oxygen or air-fuel ratio sensor with a suitable correct-specification part
- Repair or replace the heater circuit fault, including any failed fuse or relay
- Replace a faulty coolant temperature sensor or thermostat so the engine warms up properly
- Repair damaged wiring or connectors in the sensor circuits
- Repair exhaust or vacuum leaks and correct any underlying fuelling fault
- Apply a manufacturer-approved software update only where an outdated calibration is confirmed as the cause
Can I keep driving?
The car can usually be driven normally while you arrange a repair, though fuel economy and emissions may be worse. Have it checked soon, as an unresolved sensor or fuelling fault can affect the catalyst over time.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.