P0148: Fuel Delivery Error

What it means

Fuel quantity actually delivered does not match the commanded value over a long observation window. Mechanical issue in the fuel system.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test
• The engine or gearbox may go into limp mode

How it works

P0148 indicates that the fuel quantity the system delivers does not track the quantity the module commands over a sustained monitoring period. Depending on the vehicle, the module may use fuel-pressure and control data to detect a regulator, pump, restriction, sensor, or wiring problem; reduced power or a protective mode may follow.

Common causes

Most likely first.

1. Fuel pressure regulator or control valve fault
2. Fuel pressure sensor or wiring fault
3. Restricted fuel filter or line
4. Fuel pump unable to meet commanded delivery

Symptoms

• Check engine light on
• Hard starting or extended cranking
• Loss of power or hesitation
• Engine may stall

How to diagnose it

1. Use a scan tool to record freeze-frame data, commanded and actual fuel pressure or delivery values, and related fuel-system codes.
2. Inspect fuel-system connectors and wiring, especially at the pressure sensor, pump, and control valve, for loose connections, corrosion, or damage.
3. Check for restricted fuel lines or filter and verify fuel supply condition according to the manufacturer's service information.
4. Test the fuel-pressure sensor signal and its wiring against the manufacturer's specifications to rule out a false reading.
5. Measure fuel pressure and delivery under the conditions in the freeze-frame, then test the regulator, control valve, or pump as indicated.

Common fixes

• Repair a loose, corroded, or damaged fuel-pressure sensor or pump connector.
• Replace a restricted fuel filter or repair a blocked fuel line where applicable.
• Replace a faulty fuel-pressure sensor or repair its wiring if readings are incorrect.
• Repair or replace a failed pressure regulator or control valve.
• Replace a fuel pump that cannot meet commanded delivery after supply and electrical faults are ruled out.

Can I keep driving?

Avoid hard acceleration, towing, and long trips because power loss or stalling can occur unexpectedly, especially under load. If it stalls, is difficult to restart, or smells strongly of fuel, stop in a safe place and have it checked before continuing.