P023F

Fuel Pump Secondary Circuit/Open

P023F is a generic OBD-II powertrain diagnostic trouble code: Fuel Pump Secondary Circuit/Open. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P023F
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on, possible limp mode)
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What P023F means

Code P023F is stored when the Powertrain Control Module (PCM) detects an open circuit condition in the secondary fuel pump circuit. Many turbocharged, high-performance, or direct-injection vehicles use a secondary or auxiliary fuel pump — separate from the main in-tank unit — to supplement fuel delivery under high-demand conditions such as wide-open throttle or cold starting. The PCM monitors the voltage feedback from this secondary circuit to confirm the pump is receiving power when commanded. When it detects an open condition — meaning no voltage is reaching the pump or the return signal is absent — it stores P023F and illuminates the MIL. Unlike a standard fuel pump fault, this code specifically targets the secondary circuit, which has its own relay, fuse, and dedicated wiring. Because the secondary pump typically activates only under peak load, drivers may not notice a problem during light driving, but the engine may stumble, stall, or lose power under aggressive acceleration or at high engine loads where supplemental fuel flow is critical.

Common causes

Most-frequently reported root causes when P023F is logged.

  • 1
    Blown fuse in the secondary fuel pump circuit creating an open circuit
  • 2
    Failed or internally shorted secondary fuel pump relay not passing voltage to the pump
  • 3
    Broken, frayed, or heat-damaged wiring in the secondary pump supply or feedback circuit
  • 4
    Corroded or loose connector pins at the fuel pump or PCM harness
  • 5
    Defective secondary fuel pump motor (open internal winding)
  • 6
    Short to ground on the PCM relay control driver circuit
  • 7
    PCM internal failure causing incorrect relay control signal

Symptoms drivers notice

MIL illuminated
Engine stumble, hesitation, or stall under high-load acceleration
Loss of power during wide-open throttle conditions
Fuel pump running continuously with ignition off (in short-to-voltage fault scenarios)
Engine hard to start or will not start under hot-soak conditions

How to diagnose P023F

A typical diagnostic flow when this code is present.

  1. 1
    Inspect the secondary fuel pump fuse and relay; replace any blown fuse and test the relay with a known-good spare
  2. 2
    With ignition on and engine off, observe the PCM's fuel pump voltage feedback PID on a scan tool to determine if voltage is reaching the secondary circuit
  3. 3
    Remove the secondary fuel pump relay and check whether voltage remains present on the supply circuit — persistence indicates a short to voltage in the wiring
  4. 4
    Inspect the secondary pump harness for breaks, corrosion, or damage caused by heat or road debris, paying close attention to routing near exhaust components
  5. 5
    Measure resistance through the secondary pump motor windings with an ohmmeter; an open reading confirms pump failure
  6. 6
    Test the PCM relay control output circuit for continuity and check for unintended ground paths that could indicate a PCM driver failure
  7. 7
    Verify repair by clearing codes and performing a full-load test drive while monitoring fuel pump feedback voltage

Related powertrain codes

Frequently asked questions

What is the secondary fuel pump and do all vehicles have one?

The secondary fuel pump is an auxiliary unit used in addition to the main in-tank pump, typically found on turbocharged, high-performance, or direct-injection vehicles that require extra fuel flow at peak demand. Not all vehicles have one.

Will P023F always cause a no-start condition?

Not necessarily. The secondary pump typically only activates under high load, so the vehicle may start and run normally at light throttle, with problems only appearing during hard acceleration or high-speed driving.

Can a faulty relay cause P023F?

Yes. A relay with an internal short or that fails to close is one of the most common triggers for this code. Swapping the relay with a known-good one of the same type is a quick and inexpensive first diagnostic step.

Is it safe to drive with P023F?

Gentle driving at low loads may be possible, but aggressive driving or towing without a functional secondary fuel pump risks lean conditions, misfires, and potential engine damage. Repair should not be delayed.

Disabling P023F in software

RaceTune can permanently disable P023F — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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