P2D9DStarter/Generator Phase W Current Circuit Intermittent/Erratic
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2D9D covers phase W of the starter/generator when its current signal flickers or drops out for moments. The W sensor is one of the two that GM's eAssist belt machine monitors. GM's checks there look at solid failures: below -440 A or above 440 A for 41.6 ms, Type B, and a learned zero offset beyond 30 A while the inverter is off. A brief glitch that never crosses such limits is what an intermittent code is meant to catch. No manufacturer documents P2D9D publicly. Hall sensors around the phase conductors deliver a voltage that follows the current, so a drifting reference, moisture or a cracked solder joint in the electronics can make the reading jump. Steady W faults belong to other codes; U and V intermittent: P2D9B, P2D9C.
- What you may notice
- Warning lamp that shows up mostly when the engine is hot or the weather is wet
- Charging through the starter/generator briefly interrupted
- Likely causes
- PossibleMoisture inside the starter/generator electronics
- PossibleCracked solder joint in the sensor path after many heat cycles
- PossiblePoor contact in the phase W sensor connector
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €2,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.