P2044
Temperature Sensor Circuit LowP2044 is a generic OBD-II powertrain diagnostic trouble code: Temperature Sensor 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.
What P2044 means
P2044 — Reductant Temperature Sensor Circuit Low — is an SAE generic code indicating that the signal voltage from the AdBlue (DEF) fluid temperature sensor has fallen below the minimum calibrated threshold. The reductant temperature sensor is typically a two-wire NTC thermistor mounted in the AdBlue tank or in the supply/return line, and is used by the SCR controller to monitor fluid temperature for two purposes: to activate the AdBlue heating circuit in cold weather (preventing freezing below −11 °C) and to correct for temperature-dependent viscosity changes that affect dosing pump flow rate accuracy.
A low-circuit condition is most commonly caused by a short to ground in the sensor signal wire, which pulls the ECM input to near 0 V. A failed sensor with an internal short will produce the same result. Because the SCR system loses reliable temperature feedback when this code is active, the controller may default to a fixed heating-on strategy in cold weather or may flag AdBlue fluid quality as suspect since viscosity cannot be corrected. The MIL illuminates and, on some platforms, an AdBlue system warning is displayed.
The vehicle remains drivable in most cases, but the SCR system's ability to maintain target NOx conversion efficiency is reduced when temperature compensation is unavailable. On platforms with strict NOx countermeasure strategies, repeated or persistent faults can eventually trigger a torque derate.
Common causes
Most-frequently reported root causes when P2044 is logged.
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1
Short to ground in the reductant temperature sensor signal wire
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2
Failed sensor with internal short circuit
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3
Corroded or shorted sensor connector (moisture ingress shorting signal to ground)
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4
Damaged wiring harness near the AdBlue tank where it may contact the chassis
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5
Failed SCR controller input circuit (rare)
Symptoms drivers notice
How to diagnose P2044
A typical diagnostic flow when this code is present.
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1
Connect a scan tool and read live reductant temperature data; a reading at or near the minimum value (e.g. −40 °C or 0 °C fixed) when ambient temperature is warmer confirms a circuit low condition
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2
Inspect the sensor connector at the AdBlue tank for moisture, corrosion, or green oxidation — a common failure mode given the sensor's location near the wet AdBlue system
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3
Unplug the sensor connector and measure the signal pin voltage at the harness side; if still at 0 V with sensor disconnected, the short is in the wiring, not the sensor
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4
Measure sensor resistance with the connector unplugged; a reading near zero ohms confirms an internally shorted sensor
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5
Inspect the sensor wiring loom from the tank to the SCR controller for chafing against the chassis or heat source
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6
Replace the sensor if it tests shorted; clear codes and verify the signal returns to a plausible temperature reading
Related powertrain codes
- P2000 — NOx Adsorber Efficiency Below Threshold Bank 1
- P2001 — NOx Adsorber Efficiency Below Threshold Bank 2
- P2002 — Diesel Particulate Filter Efficiency Below Threshold Bank 1
- P2003 — Diesel Particulate Filter Efficiency Below Threshold Bank 2
- P2004 — Intake Manifold Runner Control Stuck Open Bank 1
- P2005 — Intake Manifold Runner Control Stuck Open Bank 2
Frequently asked questions
Does P2044 mean my AdBlue is frozen?
Not necessarily. While AdBlue freezes at −11 °C and a frozen sensor could produce unusual readings, P2044 specifically indicates a circuit low (electrical) fault. A short to ground in the wiring is a more common cause than frozen fluid.
Is P2044 dangerous to drive with?
The vehicle is drivable, but the AdBlue heating system loses temperature feedback. In cold weather this may result in improper heating control. On platforms with NOx countermeasure derates, persistent faults can eventually trigger power reduction.
Can I fix P2044 by clearing the code?
No. The code will return on the next drive cycle unless the underlying short circuit is repaired. The sensor or its wiring must be inspected and repaired.
Is the reductant temperature sensor the same as the AdBlue quality sensor?
No. Some SCR systems include a separate urea concentration (quality) sensor or use NOx sensors to infer quality. The reductant temperature sensor is dedicated to thermal monitoring and is a separate component.
Disabling P2044 in software
RaceTune can permanently disable P2044 — 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.
ECUs with a P2044 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 EDC17C60 verified 2 software versions
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