Code
P2ADE
Generic
P — Powertrain
Reductant Tank Temperature Sensor B Circuit
Views:
UK: 18
EN: 22
RU: 25
AI status
Completed
Completed
100%
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
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