Powertrain, generic (extended)

P2DC2 Starter/Generator Phase X Current Sensor Circuit Range/Performance

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

P2DC2 means the starter/generator's phase X current sensor delivers values that are electrically valid but do not make sense. CARB requires such rationality faults to be detected where feasible and kept in a code of their own, separate from wiring and out-of-limit faults. One published method is the zero check: when the inverter is not switching, no phase current flows, so the reading should be near zero. GM's eAssist machine filters this offset over eight loops and treats more than 30 A as a fault on its U and W sensors, which GM files under the Range/Performance codes of drive motor A. No manufacturer documents P2DC2 publicly. A drifting sensor zero, a corrupted reference voltage or a sensor slowly failing are likely. Circuit fault: P2DC1; high and low: P2D92, P2D95.

Likely causes

Zero point of the phase X sensor drifted, for example through ageing or heat

Sensor reference voltage out of tolerance

Phase X current sensor with gain error or slowly failing

Symptoms

Warning lamp after the plausibility check has failed on two trips
Less electric torque because current control runs in a substitute mode

Repair estimate

DifficultyHardWorkshop job

Parts and labour€150–2,000

Time0.5–4 h

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

Parts involved

starter generator phase x current sensorwiring harnessstarter generator control module

References: gsi.ext.gm.com, law.cornell.edu.