P24F3

Code

Generic P — Powertrain

Reductant Tank Temperature/Fuel Temperature Correlation

Brand: Generic

Type: P — Powertrain

Views: UK: 31 EN: 43 RU: 24

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Page language: EN

Causes

Bad/wrong reductant tank temperature sensor
Bad/wrong fuel/engine temperature sensor or reference temperature sensor
Damaged, corroded, or loose wiring/connectors between sensors and control module
Open/shorted sensor circuits or poor ground
Faulty tank heater affecting reductant temperature
Contaminated or improperly installed sensor (incorrect part or location)

Symptoms

Malfunction Indicator Lamp (MIL) or check-engine light illuminated
One or more SCR/reductant system warning lamps or messages
Reduced or disabled reductant dosing (SCR derate) leading to increased NOx emissions or limp-home behavior on some vehicles
Recorded temperature values for reductant tank and fuel/engine that differ abnormally when viewed with a scan tool
Possible diagnostic trouble codes stored for related temperature/thermal circuits

What to check

Retrieve stored freeze frame and live data with a capable scan tool; note reductant tank temp, fuel/engine temp, time, and conditions
Scan for additional related DTCs (temperature sensors, heaters, communication faults)
Visually inspect reductant tank sensor and fuel/engine temp sensor connectors for corrosion, water ingress, bent pins, or looseness
Inspect wiring harness for abrasion, chafing, heat damage, or rodent damage between sensors and module
Monitor live sensor values during key on, cold start, and warm-up; note how temperatures track together
Check operation of reductant tank heater (if equipped) and confirm correct power/ground during heater on cycles

Signal parameters

Typical sensor type: NTC thermistor or 2/3-wire temperature sensor (manufacturer dependent)
Expected signaling: voltage or resistance proportional to temperature (example ranges depend on design; many thermistors produce ~0.5–4.5 V or 1–100 kΩ resistances across operating range)
Correlation check: control module expects reductant tank temperature to follow ambient/engine/fuel temperature within a model-dependent tolerance (often within a few to tens of °C depending on conditions)
Heater circuit (if present): switched battery voltage when heater commanded and low-Ω path to ground; current draw varies by heater design

Diagnostic algorithm

Read and record all stored DTCs, freeze frame, and live data for reductant tank temp and fuel/engine temp. Note conditions (ambient temp, engine run time).
Clear codes and re-run test: monitor how values change during key-on, engine start, and warm-up to confirm repeatability.
Visually inspect both sensor connectors and wiring for damage, corrosion, or poor seating. Repair as needed.
With ignition off, disconnect sensor connectors and measure sensor resistances at ambient. Compare to manufacturer specification or typical thermistor curves. Replace sensor if out of range.
Reconnect and back-probe sensor signal with scan tool live data or DVOM to verify proper voltage response to temperature changes (warm/cool sensor with heat/cold source) and confirm sensor responds smoothly.
Check continuity and resistance of wiring between sensors and control module; repair any open/shorts. Check module grounds and power supplies for proper values.
If vehicle has a reductant tank heater, command heater ON with scan tool and verify supply voltage and heater current; replace heater or relay/fuse if inoperative.
If harness, connectors, and sensors check good but correlation fault persists, check for recent service that could have installed incorrect sensor type or position; confirm part numbers.
If all hardware checks pass, inspect for software updates or known technical service bulletins and consider reprogramming or module replacement per manufacturer guidance.
After repairs, clear codes and perform a drive/soak cycle to confirm fault does not return and SCR dosing functions normally.

Likely causes

Reductant tank temp sensor failed or intermittent
Connector corrosion or pin damage at reductant tank sensor
Fuel/engine temp sensor reading is incorrect (sensor or harness) leading to mismatch
Tank heater failed or not operating, producing an unlikely temperature difference
Incorrect sensor installed during service or repair