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Home / DTC / P2044 — Reductant Temperature Sensor A Circuit Low

P2044 — Reductant Temperature Sensor A Circuit Low

Detailed page for trouble code P2044.

32,701codes
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10,244generic
22,457specific
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Code

P2044

Generic P — Powertrain

Reductant Temperature Sensor A Circuit Low

Brand: Generic
Type: P — Powertrain
Views: UK: 16 EN: 31 RU: 19
AI status
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Page language: EN

Causes

  • Short to ground in sensor signal wire
  • Poor or corroded connector/terminal at sensor or PCM
  • Failed reductant temperature sensor (internal short or open)
  • Lost reference voltage or ground at the sensor circuit
  • Contaminated/soaked sensor or DEF ingress causing electrical fault
  • PCM/ECM internal fault (rare)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Reduced or inhibited SCR/aftertreatment function or limp mode on some vehicles
  • Aftertreatment warnings (e.g., DEF/AdBlue system messages)
  • Failed emissions inspection or failed regenerations
  • Possible drivability issues if ECM limits performance

What to check

  • Read freeze frame and failure records with a scan tool to confirm conditions when code set
  • Check for additional related DTCs (other reductant/heater/sensor codes)
  • Perform visual inspection of sensor connector, wiring harness and routing for damage, corrosion, chafing or signs of DEF contamination
  • Backprobe the sensor signal, reference and ground with key on (engine off) and compare to expected values
  • Measure sensor resistance (if safe and service information available) and compare to manufacturer spec vs temperature
  • Wiggle wiring while monitoring live data to try to reproduce fault

Signal parameters

  • Typical reductant temperature sensor signal: nominal 0.5–4.5 V (depends on vehicle and temp)
  • Low-circuit threshold: often
  • Reference supply typically 5 V (verify vehicle-specific value) and a good ground are required
  • If sensor is thermistor type, resistance will vary with temperature — consult manufacturer table for exact ohms vs °C

Diagnostic algorithm

  1. Connect a scan tool, confirm P2044 and note freeze-frame/live data (sensor voltage and reductant temperature). Clear codes and attempt to re-run to confirm repeatability.
  2. Visually inspect sensor connector and harness from sensor to PCM for damage, corrosion, moisture or DEF crystals. Repair or replace any damaged sections.
  3. With connector connected, backprobe the signal, reference and ground wires. Verify reference voltage present (usually ~5 V) and good ground. If reference missing, trace back to supply/PCM.
  4. Check signal voltage with key ON and with sensor immersed in known-temperature fluid (if service procedure available) or compare to ambient expectations. If signal is stuck low (
  5. With sensor disconnected, measure continuity from signal wire to ground to check for short. Also check continuity of reference and ground circuits to PCM.
  6. Measure sensor resistance (disconnect sensor) and compare to manufacturer spec/temperature chart. If resistance out of spec, replace sensor.
  7. Perform wiggle/stress test on wiring while monitoring live data to locate intermittent opens or shorts.
  8. If wiring and sensor test good, suspect PCM fault. Confirm with manufacturer diagnostics before replacing PCM.
  9. After repairs, clear codes and verify repairs by running vehicle to operating conditions and ensuring code does not return.

Likely causes

  • Wiring chafed and shorted to chassis ground near exhaust or DEF lines
  • Corroded connector pins at sensor allowing low voltage reading
  • Failed thermistor inside reductant temperature sensor
  • Broken or disconnected 5V reference or ground circuit to the sensor
  • DEF contamination causing sensor element to short or leak

Fault status

⚠️ Status
Reductant Temperature Sensor A circuit voltage is below normal operating range (circuit low). Possible short to ground, missing reference/ground, or failed sensor.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

P2040 P2041 P2042 P2043 P2045 P2046
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