What does code P2D99 mean?

DTC codes / P2Dxx · Hybrid propulsion / P2D99

P2D99Starter/Generator Phase Y Current Circuit Intermittent/Erratic

P2D99 indicates that the engine control module has detected an intermittent or erratic current signal on the phase Y circuit of the starter/generator unit, which is the motor-generator assembly used in mild-hybrid and some stop-start systems. The computer monitors the current flow through this phase and flags the code when the signal momentarily drops out or fluctuates outside the expected range, rather than failing completely.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaHybrid propulsion

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.