P2156Fuel Injector Group D Supply Voltage Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2156 reports the fourth shared injector supply shorted toward ground. GM's 2018 Duramax uses it only on the 6.6 L V8, where bank 4 combines injectors 3 and 8; the high-side pin reading 0.5 Ω or less to ground while switched on sets it after 5 of 10 samples, type A, lamp on the first trip. Ford's 2023 diesel summary stops at group C, so the code does not appear there. On GM petrol direct injection, as in the Saab 9-5 2.0T, P2156 stands for low voltage on the high-side control line of cylinder 4, set after 1 s and handled as type B. Since the diesel bank feeds two injectors, two cylinders cut out at once and the engine shakes noticeably. P2155 marks an open circuit and P2157 a high fault in the same group.
- What you may notice
- Two cylinders misfire together
- Strong vibration and power loss
- Check engine lamp on immediately
- Likely causes
- LikelyGroup D supply wire chafed and shorted to ground
- PossibleInjector of group D shorted to its body
- PossibleMoisture in the injector harness connector
- RareFaulty injector driver in the engine control module
- 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 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.