Low or inconsistent fuel pressure from a weak fuel pump, blocked filter or failing pressure regulator; Faulty, leaking or clogged fuel injector or injector control fault; Wiring or connector fault in the injector, fuel pump or fuel pressure sensor circuits; Faulty fuel pressure or fuel quantity control sensor or valve giving incorrect feedback; Contaminated, poor quality or wrong fuel; Air leak or fuel system leak affecting delivery measurement; Fault in the engine control unit or its driver circuits, or an outdated calibration where the manufacturer has issued an update.

P0148

Fuel Delivery Error.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
1: AreaFuel and air metering
48: FaultThe specific fault in that area

What it means

P0148 is the generic SAE J2012 code for a fuel delivery error. The engine control unit has detected that fuel delivery is not behaving as commanded, for example the fuel quantity or injection control is outside the expected range or does not match what was requested. The exact test that sets it, and the way it is monitored, depends on the manufacturer, engine and fuel system type, so check model-specific data.

Symptoms

Malfunction indicator lamp on
Hard starting or long cranking
Rough idle or misfire
Hesitation, surging or poor acceleration
Reduced power or limp mode on some vehicles
Stalling or poor fuel economy

Possible causes

Low or inconsistent fuel pressure from a weak fuel pump, blocked filter or failing pressure regulatorlikely
Faulty, leaking or clogged fuel injector or injector control faultlikely
Wiring or connector fault in the injector, fuel pump or fuel pressure sensor circuitspossible
Faulty fuel pressure or fuel quantity control sensor or valve giving incorrect feedbackpossible
Contaminated, poor quality or wrong fuelpossible
Air leak or fuel system leak affecting delivery measurementrare
Fault in the engine control unit or its driver circuits, or an outdated calibration where the manufacturer has issued an updaterare

How to diagnose

Read all stored and pending codes with freeze frame data and note engine load, temperature and rpm when the code set
Check for related codes such as fuel trim, fuel pressure, misfire or injector circuit faults and diagnose those first
Check the fuel level and ask about recent refuelling, then inspect the fuel for contamination or the wrong grade
Inspect the wiring, connectors and earths for the fuel pump, injectors and fuel pressure sensor for damage, corrosion or chafing
Check for fuel leaks and for intake or vacuum leaks, and inspect the fuel filter service history
Compare live data for fuel pressure, fuel trims and injector correction values against the manufacturer's specification
Test fuel pressure and volume against the specification, and electrically test the pump, regulator and injectors
Check for applicable service bulletins or calibration updates for the specific model and engine

How to fix

Replace a failing fuel pump, clogged fuel filter or faulty pressure regulator as confirmed by testing
Clean or replace faulty injectors as confirmed by testing
Repair damaged wiring, connectors or earths in the fuel delivery circuits
Replace a faulty fuel pressure sensor or fuel control valve
Drain and refill with correct fuel if it is contaminated, and replace the filter if needed
Update the engine control unit calibration only if the manufacturer identifies an outdated calibration as a known cause

Can I keep driving?

Medium severity

Short, gentle journeys are usually possible, but have it checked soon. If the car stalls, loses power or runs badly, stop driving, as poor fuel delivery can cause lean running, misfire and damage to the engine or catalytic converter.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.