Powertrain, generic (extended)

P2156 Fuel Injector Group D Supply Voltage Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

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.

Likely causes

Group D supply wire chafed and shorted to ground
Injector of group D shorted to its body
Moisture in the injector harness connector
Faulty injector driver in the engine control module

Symptoms

  • Two cylinders misfire together
  • Strong vibration and power loss
  • Check engine lamp on immediately

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–1,500
Time1–5 h

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

Parts involved

fuel injectorinjector wiringengine control module

Related codes

P2155P2157P2153P2147P0270

References: gsi.ext.gm.com, gsi.ext.gm.com, saabwisonline.com.