P056ECold Start Turbocharger/Supercharger Boost Control A Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- 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.
- What you may notice
- Check engine light on
- Hard cold start or rough warm-up
- Otherwise usually unremarkable
- Likely causes
- LikelyVariable turbine or wastegate actuator stiff (coking, cold)
- PossibleModule software or calibration
- PossibleVacuum or boost hose leaking
- RarePosition or boost sensor faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €0 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.