P24DA

Reductant Pump Control Circuit High

P24DA is a generic OBD-II powertrain diagnostic trouble code: Reductant Pump Control Circuit High. 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
P24DA
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on, possible limp mode)
Need P24DA disabled?
RaceTune permanently disables any OBD-II trouble code on supported ECUs — for motorsport, off-road, and export use.
→

What P24DA means

P24DA indicates the ECM/PCM has detected a higher-than-expected voltage on the control circuit of the DEF (diesel exhaust fluid / reductant) pump. This typically means the control signal wire is shorted to a power source, the pump driver circuit inside the module has failed in an open-load condition, or a relay or actuator associated with the pump is causing the circuit to read high when it should be driven low.

The reductant pump is responsible for pressurising DEF from the tank and delivering it to the dosing injector upstream of the SCR catalyst. When the pump control circuit is faulted, the module cannot confirm correct pump operation, and DEF delivery may cease or become uncontrolled. This directly compromises SCR NOx reduction efficiency.

Continued operation without DEF dosing will cause NOx emissions to exceed legal limits. Depending on the vehicle manufacturer's strategy, a torque reduction or speed limiter (derate) may be activated after a defined number of drive cycles with this fault present, making prompt repair important.

Common causes

Most-frequently reported root causes when P24DA is logged.

  • 1
    Short to battery voltage on the reductant pump control signal wire.
  • 2
    Failed reductant pump motor with an internal short causing back-voltage on the circuit.
  • 3
    Faulty ECM/PCM pump driver output stage.
  • 4
    Corroded or damaged pump connector causing high-resistance contact that reads as high voltage.
  • 5
    Failed relay in the reductant pump supply circuit stuck in the energised position.
  • 6
    Wiring harness damage near the pump or DEF tank where heat or abrasion is common.

Symptoms drivers notice

MIL and/or SCR warning lamp illuminated.
DEF dosing reduced or suspended, leading to elevated NOx emissions.
Potential torque derate or speed limiter activation after repeated fault cycles.
Possible DEF pump inoperative (no audible prime on key-on).
Other SCR-related codes may accompany this fault.

How to diagnose P24DA

A typical diagnostic flow when this code is present.

  1. 1
    Record all DTCs and freeze-frame data with a scan tool prior to any repairs.
  2. 2
    Inspect the reductant pump connector and wiring for visible damage, corrosion, or chafed insulation.
  3. 3
    With the connector unplugged from the pump, measure voltage on the control circuit wire; a high reading with the circuit open indicates a short to power in the harness.
  4. 4
    Check for voltage at the pump supply circuit to confirm the relay and fuse are functioning correctly.
  5. 5
    If harness integrity is confirmed, test the pump motor winding resistance and compare to specification.
  6. 6
    Check ECM/PCM output driver with a test light or oscilloscope; if the driver does not command the circuit low when expected, suspect an internal module fault.
  7. 7
    Repair wiring or replace the pump as indicated; clear codes and verify repair with a functional drive cycle.

Related powertrain codes

Frequently asked questions

Will P24DA cause a torque derate immediately?

Not always immediately. Most manufacturers allow a grace period of several drive cycles before activating a derate, but this varies by calibration. Do not ignore the fault.

Can low DEF level cause P24DA?

Low DEF level typically sets different codes related to level or quality. P24DA is specifically a pump control circuit high voltage fault, not a fluid level issue.

Is P24DA the same as a pump failure code?

No. P24DA is a circuit fault (high voltage on the control line). The pump itself may be fine; the fault may be entirely in the wiring or the ECM driver.

Can I reset the derate counter after repair?

Yes. After repairing the fault and clearing the DTCs, most systems require a successful SCR system verification drive cycle to reset any active derate condition. A scan tool with bi-directional SCR test capability can accelerate this.

Disabling P24DA in software

RaceTune can permanently disable P24DA — 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.

Got P24DA in your scan?

Upload your ECU file — we'll identify the exact software version and confirm whether a disable is available for your car.

Upload your file