P24EA

Reductant Tank Temperature Sensor Circuit High

P24EA is a generic OBD-II powertrain diagnostic trouble code: Reductant Tank Temperature Sensor 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
P24EA
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on)
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What P24EA means

P24EA is stored when the ECM detects that the DEF tank temperature sensor signal voltage is above the expected maximum threshold. In a typical NTC thermistor-based system, excessively high signal voltage indicates an open circuit in the signal or ground path, preventing the sensor from completing its voltage divider network. The ECM sees a voltage reading that corresponds to an impossibly cold temperature or is simply outside the valid operating range.

A circuit-high fault most commonly results from an open sensor signal wire, an open sensor ground path, or a failed sensor with an internal open circuit. Connector pull-outs and harness damage in the DEF system routing, which is exposed to thermal cycling and chemical exposure from DEF, are frequent root causes. The fault can also be triggered by a failed ECM reference supply that is stuck high without a return path.

With this fault active, the ECM cannot determine DEF tank temperature and may over-heat or under-heat the tank depending on the default strategy. Over-heating wastes energy and accelerates DEF degradation; under-heating allows freezing. Diagnosis should begin with connector and wiring inspection, followed by sensor resistance verification and signal voltage checks with the circuit disconnected.

Common causes

Most-frequently reported root causes when P24EA is logged.

  • 1
    Open circuit in the temperature sensor signal wire.
  • 2
    Open sensor ground path preventing circuit completion.
  • 3
    Failed DEF tank temperature sensor with internal open circuit.
  • 4
    Disconnected or backed-out terminal in the sensor connector.
  • 5
    Wiring harness damage (chafing, heat damage) in the DEF system routing.
  • 6
    Corroded terminal causing high-resistance open condition.
  • 7
    ECM input circuit fault.

Symptoms drivers notice

MIL illuminated.
DEF system warning indicator may be active.
Improper DEF tank heater operation.
Potential DEF overheating or failure to thaw in cold weather.
No drivability impact in typical ambient conditions.

How to diagnose P24EA

A typical diagnostic flow when this code is present.

  1. 1
    Connect a scan tool and retrieve all DTCs; note freeze frame ambient conditions.
  2. 2
    Inspect the DEF tank temperature sensor connector for backed-out terminals, corrosion, or DEF contamination.
  3. 3
    Measure the sensor signal voltage with the connector connected and ignition on; near-5V confirms circuit-high.
  4. 4
    Disconnect the sensor and jumper the signal wire to ground; if voltage drops, the sensor has an internal open.
  5. 5
    Measure sensor resistance across the sensor terminals at ambient temperature.
  6. 6
    Inspect the sensor ground wire for continuity from the connector back to the ECM or chassis ground.
  7. 7
    Replace the sensor if resistance is out of specification or internal open is confirmed.

Vehicles where we've handled P24EA

Platforms in our catalogue with confirmed P24EA coverage.

BMW 320D
2016

Related powertrain codes

Frequently asked questions

How does an open circuit cause a high voltage reading?

In a voltage divider circuit, the ECM pulls the signal line to 5V through an internal resistor. When the sensor is disconnected or open, there is no return path to pull the voltage down, so the signal line floats near 5V, triggering the circuit-high fault.

Is P24EA the opposite of P24E8?

Yes. P24E8 is circuit low (signal shorted toward ground) while P24EA is circuit high (signal open or floating toward the reference voltage). Both indicate sensor circuit faults but with opposite electrical signatures.

Can I drive with P24EA without damage?

In moderate temperatures, short-term driving is generally safe. In freezing conditions, the DEF heater may not operate correctly, risking frozen DEF and loss of SCR function.

Can a corroded terminal cause P24EA?

Yes. High-resistance corrosion in the signal or ground path can effectively create an open circuit condition, causing the signal to float high and triggering the circuit-high diagnostic.

Disabling P24EA in software

RaceTune can permanently disable P24EA — 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 P24EA 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 EDC17C50 verified 1 software version
  • 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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