Powertrain, generic (extended)

P2DD5 Fuel Injection Quantity B Lower Than Expected

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P2DD5 reports that the injection path the manufacturer calls B delivers less fuel than the engine control commanded. SAE leaves open what B is: a second injector set, an injector group or a separate operating mode. No manufacturer documents this code publicly. The underlying check is the one CARB has demanded from diesels since 2010: the module compares requested fuel with what airflow and lambda say was burned. GM does this for system A as an adaptation (FSA) with a lower threshold map, 200 of 400 samples, Type B; Ford diesels report a fueling error below -0.15 as P0171. P2DD6 is the opposite direction, P2DD7 the cold-start version. Expect weak pull and possibly rough running.

Likely causes

Injectors of group B coked or partly blocked
Supply or rail pressure for this path too low (filter, pump)
Airflow or lambda measurement off, so the computed fuel looks too small
Engine control software or injector calibration data

Symptoms

  • Check engine light on
  • Less power, sluggish response under load
  • Uneven idle

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–3,000
Time0.5–5 h

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

Parts involved

fuel injector group bfuel railecm

Related codes

P2DD6P2DD7P026CP2DDCP2DDEP0171

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