P2ADE

Code

Generic P — Powertrain

Reductant Tank Temperature Sensor B Circuit

Brand: Generic

Type: P — Powertrain

Views: UK: 18 EN: 30 RU: 33

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Page language: EN

Causes

Open circuit in sensor B wiring
Short to ground or short to battery in sensor B wiring
Corroded, loose or contaminated connector at sensor B
Failed reductant tank temperature sensor (B)
Contaminated or frozen reductant (crystals, water/ice) affecting sensor reading
Damaged harness (chafing, broken conductors)

Symptoms

Malfunction Indicator Lamp (MIL) or emissions warning lit
SCR or DEF system warning message on dash
Reduced ability to perform active regeneration or SCR derate
Stored fault code(s) related to reductant temperature or SCR
Possible failure to reach correct reductant temperature for dosing/regeneration

What to check

Scan tool: read freeze frame and live data for reductant tank temperature (Sensor B) and related codes
Visual inspection of sensor B, connector, and harness for corrosion, damage, or contamination
Check for presence of reductant (fluid level) and signs of crystallization or freezing
Verify appropriate fuses and grounds for SCR/reductant sensors
Backprobe connector to measure signal voltage with key ON (engine OFF) and compare to expected
Measure sensor resistance at the sensor with connector disconnected and compare to spec

Signal parameters

Typical reference: 5.0 V sensor reference (varies by manufacturer); ECM reads voltage from temperature divider
Common NTC thermistor example (approximate): R ≈ 33 kΩ at 0°C, ≈ 10 kΩ at 25°C, ≈ 1.3 kΩ at 80°C (sensor-dependent)
Approximate expected signal voltages (with 5 V reference & 10 kΩ pull-up example): ~3.8 V at 0°C, ~2.5 V at 25°C, ~0.6 V at 80°C
Fault thresholds (generic): open circuit if sensor resistance >> normal (eg. >45 kΩ) or voltage ≈ supply ( >4.5 V); short if resistance
Actual resistance/voltage values vary by vehicle — always compare to manufacturer data where available

Diagnostic algorithm

Use a scan tool: record DTC P2ADE and any related codes (e.g., sensor A, heater circuits). Note freeze-frame and live reductant temperature values.
Visually inspect sensor B, connector, and wiring along the harness for damage, corrosion, crushed wires, or contamination. Repair as needed.
With key ON (engine OFF) backprobe the sensor signal pin and measure voltage. Compare to expected voltage for ambient temperature. If voltage is out of range, proceed to wiring checks.
Disconnect sensor B and measure resistance across sensor terminals at ambient temperature. Compare to expected resistance curve or manufacturer spec. Replace sensor if out of spec.
Perform wiring continuity check from sensor connector to the ECU pin. Check for short to ground and short to battery between signal and supply/ground circuits.
If the sensor and wiring test OK, swap connector to sensor A (if identical and permissible) or substitute a known-good sensor to isolate ECU vs sensor/harness.
Inspect for external causes: frozen or crystallized DEF around sensor, low fluid level, or contamination that could affect readings. Clean or service tank as required.
Repair or replace faulty sensor, connector, or wiring. Secure and protect harness from future damage.
Clear codes, perform readiness tests and, if required, run system checks or vehicle drive cycle to confirm repair. Re-scan for recurrence.

Likely causes

Failed temperature sensor B
Connector corrosion or water ingress at the sensor
Open or shorted signal wire between sensor B and ECM
High resistance due to damaged insulation or poor pin contact
Reductant contamination or crystallization around sensor

Fault status

⚠️ Status

P2ADE — Reductant Tank Temperature Sensor B Circuit: Control module detected open, short, or implausible signal from reductant tank temperature sensor B. May affect SCR/DEF control and emissions monitoring.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours