P24D1

Reductant Pump Control Circuit

P24D1 is a generic OBD-II powertrain diagnostic trouble code: Reductant Pump Control Circuit. 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
P24D1
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on)
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What P24D1 means

P24D1 is stored when the ECM detects a fault in the electrical control circuit for the DEF (reductant) supply pump. The pump is responsible for pressurizing the DEF supply line so that the dosing module can accurately meter reductant into the exhaust stream. The ECM monitors the pump control circuit for open-circuit, short-to-ground, and short-to-voltage conditions.

This code differs from pump performance codes in that it specifically indicates an electrical circuit fault rather than an insufficient pressure or flow outcome. The pump motor may not operate at all when P24D1 is active, which will lead to zero DEF delivery and rapid SCR system failure if the condition persists. In cold climates, even a brief loss of pump operation can prevent SCR activation within the required warm-up time.

Diagnosis should begin with circuit resistance and voltage checks at the pump connector. Common failure modes include harness damage in the DEF system's heated lines (which can also damage nearby wiring), connector corrosion from DEF spillage, and failed ECM pump driver circuits.

Common causes

Most-frequently reported root causes when P24D1 is logged.

  • 1
    Open circuit in the DEF pump control wiring harness.
  • 2
    Short to ground in the pump control or supply circuit.
  • 3
    Short to voltage in the pump control circuit.
  • 4
    Corroded or contaminated pump electrical connector from DEF spillage.
  • 5
    Failed ECM or SCR module pump driver.
  • 6
    Blown fuse in the pump supply circuit.
  • 7
    Failed DEF pump motor causing excessive current draw and driver shutdown.

Symptoms drivers notice

MIL illuminated.
DEF pump may not operate, resulting in no system pressure.
SCR system will not dose DEF, leading to NOx performance faults.
DEF warning indicator on instrument cluster.
Possible torque derate after extended non-dosing period.

How to diagnose P24D1

A typical diagnostic flow when this code is present.

  1. 1
    Connect a scan tool and retrieve all DTCs and freeze frame data.
  2. 2
    Check the DEF pump fuse in the fuse box and replace if blown.
  3. 3
    Inspect the pump connector and wiring for corrosion, DEF contamination, or damage.
  4. 4
    Measure supply voltage at the pump connector with ignition on.
  5. 5
    Measure pump control circuit resistance from the ECM connector to the pump.
  6. 6
    Command the pump on via the scan tool and measure current draw at the pump supply circuit.
  7. 7
    Replace the pump if voltage and wiring are confirmed good but the pump does not operate.

Related powertrain codes

Frequently asked questions

Can DEF spillage damage the pump wiring?

Yes. DEF (urea solution) is mildly corrosive and can degrade connector terminals and wire insulation over time, particularly at the pump connector. Cleaning with distilled water and applying dielectric grease is recommended.

Will the vehicle derate immediately with P24D1?

Most calibrations allow a grace period before initiating derate. However, since the pump is not operating, DEF delivery stops immediately and NOx faults may accumulate quickly.

Is P24D1 the same as the pump failing mechanically?

Not necessarily. P24D1 is an electrical circuit fault. A mechanically seized pump can cause a circuit fault if the stall current trips the driver, but circuit faults from wiring damage are equally common.

Can I test the DEF pump directly to confirm it works?

Yes. Applying the correct supply voltage directly to the pump terminals (observing polarity) will confirm motor operation independent of the ECM circuit, helping to isolate a wiring fault from a pump failure.

Disabling P24D1 in software

RaceTune can permanently disable P24D1 — 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.

ECUs with a P24D1 disable in our catalogue

Confirmed coverage from our recipe database — we support many more families. Upload your file and our identifier will match it automatically.

  • Bosch EDC17CP09 verified 1 software version

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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