P24F4

Reductant Injection Valve Control Circuit Low

P24F4 is a generic OBD-II powertrain diagnostic trouble code: Reductant Injection Valve Control Circuit Low. 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
P24F4
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on, possible limp mode)
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What P24F4 means

P24F4 is set when the ECM/PCM detects a lower-than-expected voltage on the control circuit of the DEF dosing injector valve. A circuit low condition typically indicates a short to ground somewhere in the wiring between the module and the injector, or an internal short within the injector solenoid coil itself. The module detects that the circuit is being pulled low when it should be at a commanded high state or at rest voltage.

Unlike an open-circuit code, a short to ground may cause continuous or uncontrolled injector activation, which can over-dose DEF into the exhaust and potentially flood or damage the SCR catalyst or DPF. The ECM will typically disable the injector drive to protect the system, meaning DEF dosing will cease despite the short.

SCR efficiency will be compromised with this fault active. Depending on the OEM calibration, a derate strategy may activate within a defined number of drive cycles. The risk of catalyst contamination from DEF flooding makes prompt repair especially important with this fault code.

Common causes

Most-frequently reported root causes when P24F4 is logged.

  • 1
    Short to ground on the dosing injector control signal wire.
  • 2
    Internal short in the injector solenoid coil winding.
  • 3
    Pinched or chafed wiring harness where insulation has worn through to a grounded surface.
  • 4
    Water or DEF fluid intrusion into the injector electrical connector causing a leakage path to ground.
  • 5
    Faulty ECM/PCM internal driver shorted to ground.
  • 6
    Damaged wiring near the exhaust tunnel or DEF module bracket.

Symptoms drivers notice

MIL and SCR/AdBlue warning lamp on.
DEF dosing suspended by the ECM to protect the system.
Elevated NOx emissions due to loss of SCR function.
Possible torque or speed derate after repeated fault cycles.
Potential DEF over-injection and catalyst damage if the fault is intermittent and not caught quickly.

How to diagnose P24F4

A typical diagnostic flow when this code is present.

  1. 1
    Read and record all DTCs and freeze-frame data with a scan tool.
  2. 2
    Inspect the dosing injector wiring harness and connector for signs of chafing, moisture ingress, or contact with hot exhaust surfaces.
  3. 3
    Disconnect the injector and measure resistance from the control circuit wire to chassis ground; a low resistance reading confirms a short to ground in the harness.
  4. 4
    Measure injector coil resistance at the injector terminals; a very low or zero reading indicates an internal short in the coil.
  5. 5
    Check the wiring harness routing for contact points with the exhaust system where heat could damage insulation.
  6. 6
    If harness and connector check out, perform an ECM driver output test to rule out an internal module fault.
  7. 7
    Replace the injector or repair the harness as indicated, clear codes, and verify with a functional drive cycle.

Related powertrain codes

Frequently asked questions

Is P24F4 more serious than P24F3?

P24F4 (short to ground) can be more damaging than P24F3 (open circuit) because uncontrolled DEF injection risks saturating the SCR catalyst before the ECM disables the driver.

Can moisture in the connector cause P24F4?

Yes. Liquid DEF or water bridging the signal pin to a grounded shell in the connector is a common cause of a circuit low condition.

Will the fault go away if I dry out the connector?

It may clear temporarily, but if the connector seal is compromised, moisture will return. Clean, dry, and apply dielectric grease, but also address the root cause of the moisture entry.

Can P24F4 damage the ECM?

A sustained short to ground can stress the ECM driver circuit. Modern ECMs have protection circuitry, but repeated or prolonged shorts can cause driver failure. Repair promptly.

Disabling P24F4 in software

RaceTune can permanently disable P24F4 — 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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