What it means
At idle the ECU expects a calibrated fuel quantity to maintain set-speed. The actual quantity is significantly less than modelled - typical for a tight engine, very low friction, dragging accessory load missing, or implausible idle airflow.
At a glance
- Usually lights the check-engine light
How it works
At idle, the control module estimates how much fuel the engine needs to maintain its target speed. P054E sets when the calculated fuel quantity is lower than the module expects, so check whether airflow, fuel delivery, or an engine-load input is making that estimate inaccurate.
Common causes
Most likely first.
- Idle air or fuel control issue affecting the calculated fuel quantity
- Air leak or incorrect airflow measurement
- Fuel delivery problem
- Incorrect engine load or sensor input
Symptoms
- Check-engine light on
- Rough or unstable idle
- Possible stalling at idle
How to diagnose it
- Read freeze-frame data and live idle values for engine speed, airflow, fuel trims, and calculated load to see when the fuel-quantity mismatch occurs.
- Check whether idle speed is stable and inspect intake hoses and vacuum connections for leaks that could distort measured airflow.
- Compare airflow and engine-load sensor readings at idle with the manufacturer's specifications to find an implausible input.
- Check fuel-pressure and fuel-delivery data against the manufacturer's specification if the airflow and load readings appear reasonable.
- Review idle-control and fuel-command data to determine whether the module is reducing fuel because of an air-control or mixture problem.
- If basic checks do not explain the low calculated quantity, test related sensors and idle-control components using the manufacturer's procedure.
Common fixes
- Reconnect or replace a leaking intake hose or vacuum line.
- Clean or repair a contaminated or faulty airflow sensor if its readings are inaccurate.
- Repair a fuel-delivery fault identified by pressure or command checks.
- Repair an idle-air control fault that is causing an incorrect fuel calculation.
- Correct a faulty engine-load or other sensor input.
Can I keep driving?
If the engine idles steadily, short local trips may be manageable, but avoid situations where a stall would be hazardous. Stop driving if it stalls repeatedly or cannot maintain idle, since loss of engine power can affect maneuvering.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.