Powertrain, generic (extended)

P2AD8 Reductant Pump Motor Position Sensor Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2AD8 reports a reductant pump motor position signal stuck below its valid range. For Hall-type sensors this mostly means the output is pulled to ground permanently: a signal wire shorted to ground, a sensor that has lost its supply, or an internal short in the pump electronics. Without a usable rotor position a brushless pump motor cannot be commutated reliably any more, so the controller may stop the pump to protect it. No manufacturer publishes P2AD8 or a threshold; the general frame is the CARB requirement for circuit checks on emission-relevant inputs. Where the sensor wiring runs inside a sealed pump module, check the external harness, fuses and supply voltage at the pump connector first; if those are sound, the pump unit is the likely replacement.

Likely causes

Internal short in the pump electronics
Position signal shorted to ground
Sensor supply missing, e.g. blown fuse or open feed

Symptoms

  • Check engine light and SCR warning
  • DEF pump does not run, no dosing

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€300–1,500
Time1–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

reductant pump motor position sensorreductant pumpwiring harness

Related codes

P2AD6P2AD9P2AD7P208C

References: law.cornell.edu, patents.google.com.