P2AD9

Code

Generic P — Powertrain

Reductant Pump Motor Position Sensor Circuit High

Brand: Generic

Type: P — Powertrain

Views: UK: 26 EN: 27 RU: 22

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Malfunction Indicator Lamp (MIL) illuminated with P2AD9 stored
Reduced or disabled reductant dosing; regen failures or reduced engine power in limp mode
Reductant pump may not operate correctly (runs continuously or not at all)
Possible diagnostic trouble codes related to reductant/DEF system or NOx control
Noisy or inconsistent position sensor PID values in live data

Retrieve all stored codes and freeze frame/live data with a capable scan tool
Visually inspect wiring and connectors at the reductant pump and ECM for damage, corrosion, bent pins, or water intrusion
Backprobe the sensor connector and monitor signal voltage and ground with key ON/engine OFF and during pump operation
Wiggle test harness while monitoring the sensor signal for intermittent changes
Check for battery voltage on the sensor signal wire (indicates short to B+)
Measure reference voltage and ground continuity between sensor connector and ECM connector

Typical position sensor is a variable voltage (0.5–4.5 V) or PWM-derived analog signal; exact range depends on manufacturer
Circuit HIGH generally defined as a signal near battery voltage or above the expected maximum (e.g., >4.5–4.8 V) or an implausible fixed high value
With pump movement, sensor voltage should vary smoothly across its range; abrupt fixed high indicates fault
Reference and ground should be stable (reference often ~5 V); loss of ground can drive signal high

Read and record all DTCs, freeze frame and live data. Note conditions when P2AD9 set.
Inspect connectors and wiring at the reductant pump and ECM for damage, corrosion, loose pins, or water. Repair as needed.
With ignition ON (engine OFF), backprobe the sensor signal, reference and ground pins. Verify reference voltage (if present), signal voltage and ground continuity to ECM. Compare to expected ranges.
If signal reads high (~battery voltage), disconnect the sensor connector. If the signal at the harness remains high with sensor disconnected, suspect wiring short to B+ or ECM pin fault.
Check for short to B+: measure voltage between signal wire and ground; use wiring diagrams to locate and inspect any splice points, relays or connectors that could feed B+ into the circuit.
If harness checks out (no short), test sensor by measuring resistance or output while actuating pump/position (if accessible) per manufacturer specification. Replace pump assembly if sensor internal failure is confirmed.
If wiring and sensor test good but problem persists, inspect ECM connector pins and wiring continuity to ECM; repair or replace as required.
After repairs, clear codes and perform function test and road/drive cycle to verify DTC does not return. Re-scan for related codes and ensure reductant dosing functions normally.

Corroded connector at the reductant pump leading to intermittent high-voltage reading
Short to battery voltage on the sensor signal wire due to chafing or pin contact
Failed position sensor inside the reductant pump assembly
Poor ground at the pump or harness causing abnormal sensor voltage