P056E

What it means

P056E is a generic code for Cold Start Turbocharger/Supercharger Boost Control 'A' Performance. The engine control unit compared actual boost pressure with the target while the engine was cold, and the two did not match as expected. The 'A' usually refers to the first boost control device or circuit, such as a wastegate or variable geometry actuator, but the exact layout depends on the engine.

Symptoms

• Engine warning light on
• Lack of power or sluggish acceleration when cold
• Boost lower or higher than normal on a cold engine
• Limp mode or reduced torque after a cold start
• Whistling, hissing or fluttering from the intake or turbo area
• Possible black or blue smoke on cold starts

Possible causes

• Boost leak from a split or loose charge air hose, intercooler joint or clamplikely
• Wastegate or variable geometry actuator sticking, slow or out of adjustment, often worse when coldlikely
• Faulty or leaking boost control solenoid, vacuum line or vacuum supplylikely
• Boost pressure, manifold pressure or intake air temperature sensor reading incorrectlypossible
• Wiring or connector fault on the actuator, solenoid or sensorspossible
• Worn turbocharger, or oil or carbon contamination of the vanespossible
• Outdated engine control software where the manufacturer lists it as a known cause for the modelrare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting coolant temperature, engine load and target versus actual boost.
2. Check for other related codes such as boost sensor, actuator or air flow faults, and deal with those first.
3. Visually inspect the charge air hoses, clamps, intercooler and intake joints for splits, oil residue or looseness.
4. Inspect the wiring and connectors to the boost control solenoid, actuator and boost sensors for damage, corrosion or chafing.
5. Inspect vacuum hoses and check the vacuum supply to the actuator, where fitted, for leaks or cracks.
6. Compare live data for target and actual boost, and sensor readings with the engine cold and again when warm.
7. Command the actuator or solenoid with a diagnostic scan tool and check it moves freely and smoothly, and that its feedback matches.
8. Pressure test the intake system for leaks, and check turbo shaft play and vane movement, following the procedure for your engine.

How to fix

• Repair or replace leaking or damaged charge air hoses, clamps or intercooler parts.
• Replace or free up a sticking wastegate or variable geometry actuator, and set it up as the manufacturer specifies.
• Replace a faulty boost control solenoid or perished vacuum lines.
• Replace any boost, manifold pressure or intake temperature sensor found to be out of range.
• Repair damaged wiring or connectors, and clear the code once the fault is fixed.
• Repair or replace the turbocharger if it is worn or its vanes are seized, and correct the cause of any oil contamination.

Can I keep driving?

Nearby codes

• P056DGenericReductant Control Module System Voltage
• P056FGenericCold Start Turbocharger/Supercharger Boost Control B Performance