Powertrain, generic · Vehicle speed, idle control and auxiliary inputs

P056E Cold Start Turbocharger/Supercharger Boost Control A Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

CARB requires every element commanded by the cold-start strategy to respond measurably in the commanded direction, with its own codes separate from the general monitoring of the same part. During catalyst heating the boost control is positioned deliberately – diesels close the variable turbine for load and heat, petrol engines open the wastegate so heat reaches the catalyst. P056E means boost control A (the first or only charger) did not follow its cold-start target. Its only documented user is Stellantis: the 2025 Ram 3500 cab chassis with 6.7 L Cummins lists it among codes that can light the warning lamp, fixed by a PCM software update; customers noticed hard cold starts and raised cold idle. Ford and GM do not use it.

Likely causes

Variable turbine or wastegate actuator stiff (coking, cold)
Module software or calibration
Vacuum or boost hose leaking
Position or boost sensor faulty

Symptoms

  • Check engine light on
  • Hard cold start or rough warm-up
  • Otherwise usually unremarkable

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–1,500
Time0.5–4 h

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

Parts involved

turbocharger actuatorboost pressure sensorengine control module

Related codes

P056FP0299P0234P2563P050AP052A

References: static.nhtsa.gov, law.cornell.edu.