Fuel and air

P0148 — Fuel Delivery Error

Severity: medium Drive with care, to a shop

What P0148 means

The engine control unit compares the commanded fuel pressure or quantity with what the engine actually receives, based on sensor signals. If the mismatch lasts too long, it stores P0148 and turns on the check engine light. The cause may be in the fuel system itself, or in a sensor or its wiring.

Symptoms

  • Check engine light on
  • Loss of power and weak acceleration
  • Rough idle or hesitation when accelerating
  • Hard starting or occasional stalling
  • Higher fuel consumption
  • Fuel smell or smoke from the exhaust

Possible causes

  1. Low or unstable fuel rail pressure
  2. Weak fuel pump (or high-pressure pump on a diesel)
  3. Clogged fuel filter or restricted fuel lines
  4. Faulty fuel pressure sensor
  5. Leaks in the fuel system
  6. Damaged wiring or corroded connectors
  7. Rarely, an ECM fault or software problem

How to diagnose

  1. Scan all codes and freeze frame data and look for other fuel or mixture-related codes.
  2. Inspect fuel lines, the rail and fittings for leaks or fuel smell.
  3. Measure actual fuel pressure with a gauge and compare it with the spec for the engine.
  4. Compare the scan tool fuel pressure reading with the gauge to separate a bad sensor from a real pressure problem.
  5. Check pump power, relay, fuse and ground.
  6. Inspect the wiring and connectors at the sensor and pump for damage or corrosion.
  7. Check filter condition and pump flow volume.
  8. If the fuel side is fine, check ECM power and look for software updates.

Common fixes

  • Replace the fuel pump or high-pressure pump
  • Replace the fuel filter
  • Replace the fuel pressure sensor
  • Repair leaks and replace damaged fuel lines
  • Repair wiring and connectors
  • Reprogram or replace the ECM (rare)

Questions and answers

What does P0148 mean?

The ECM found that fuel delivery or pressure does not match the target. Check the pump, filter, lines, pressure sensor and wiring.

Can I drive with code P0148?

Only a short distance for diagnosis. The engine may lose power or stall, and a lean mixture can cause damage.

Can I just clear P0148?

Clearing it only turns the light off for a while. If the cause is not fixed, the code will return and the problem may get worse.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.