P241D

Reductant Tank Heater Control Circuit

P241D is a generic OBD-II powertrain diagnostic trouble code: Reductant Tank Heater 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
P241D
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on)
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What P241D means

P241D indicates that the PCM or diesel exhaust aftertreatment control module has detected a fault in the electrical control circuit for the diesel exhaust fluid (DEF) tank heater. The DEF tank heater is critical in cold climates because urea-water solution freezes at approximately -11 degrees Celsius (12 degrees Fahrenheit). Without a functional heater, the SCR system cannot deliver reductant to the NOx catalyst, causing elevated NOx emissions and, on many platforms, an inducement strategy that progressively limits engine power.

A circuit fault on this code can reflect an open, short to ground, or short to voltage anywhere between the control module and the heater element or relay. It may also be triggered by an internal heater element failure resulting in resistance outside the expected range. The control module typically monitors the circuit for proper current draw when the heater is commanded on.

Diagnosis should begin with a visual inspection of the heater wiring harness and connector, as DEF is corrosive and can degrade connectors over time. Live data showing commanded heater state versus actual circuit feedback will help isolate whether the fault is in the heater element itself or upstream wiring.

Common causes

Most-frequently reported root causes when P241D is logged.

  • 1
    Open circuit in the DEF tank heater wiring harness or connector.
  • 2
    Short to ground or short to voltage in the heater control wiring.
  • 3
    Failed DEF tank heater element with resistance out of specification.
  • 4
    Corroded or DEF-contaminated heater connector causing high resistance.
  • 5
    Faulty heater relay not switching power to the element.
  • 6
    Control module driver failure unable to energize the heater circuit.

Symptoms drivers notice

MIL or amber warning lamp illuminated.
DEF system inoperative warning on instrument cluster in cold conditions.
Potential power limitation or inducement strategy activated if DEF delivery fails.
SCR NOx efficiency monitor setting additional faults if heater fault persists.

How to diagnose P241D

A typical diagnostic flow when this code is present.

  1. 1
    Retrieve all stored DTCs and note any companion SCR or DEF quality/level codes.
  2. 2
    Visually inspect the DEF tank heater connector and harness for corrosion, DEF crystallization, or chafing.
  3. 3
    Measure resistance of the heater element at the connector and compare to specification.
  4. 4
    Check for battery voltage at the heater relay or fuse supplying the heater circuit.
  5. 5
    Command the heater on with a scan tool and measure current draw; compare to expected value.
  6. 6
    If wiring and element are good, test the relay and control module output before replacing the module.

Related powertrain codes

Frequently asked questions

Can P241D cause an engine derate?

Yes, on many diesel platforms a persistent DEF system fault activates an inducement strategy that progressively reduces engine power until the fault is repaired.

Is DEF harmful to connectors?

DEF (urea solution) is mildly corrosive to certain metals; crystallized deposits can bridge connector pins and cause circuit faults, so connectors in this area need periodic inspection.

Does P241D only set in cold weather?

The heater circuit fault can set at any ambient temperature, but the heater is only commanded on when temperatures approach the freezing point of DEF, so the fault may appear seasonally.

Can I clear P241D and continue driving?

Clearing the code allows temporary operation, but if the heater is genuinely inoperative in freezing conditions the SCR system will fail and inducement may reactivate.

Disabling P241D in software

RaceTune can permanently disable P241D — 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 P241D 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 EDC17C56 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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