P0046

What it means

P0046 is the generic SAE J2012 code for a range or performance fault in the turbocharger or supercharger boost control 'A' circuit. The engine control unit has judged that the boost control device, such as a wastegate or variable geometry actuator, is not responding or positioning as commanded. Typically the measured boost or actuator position has differed from the target by more than allowed for a set period.

Symptoms

• Engine warning light on
• Loss of power or reduced boost, often with limp mode
• Turbo feels sluggish, or boost builds late
• Overboost surge or erratic power delivery
• Whistling, fluttering or unusual turbo noises
• Poorer fuel economy

Possible causes

• Boost control solenoid or electric actuator sticking, worn or failinglikely
• Boost pressure leaks from hoses, clamps, intercooler or intake pipeworklikely
• Vacuum line to the actuator split, disconnected or blocked, or weak vacuum supplypossible
• Wastegate or variable geometry mechanism seized, carbon-clogged or linkage wornpossible
• Wiring or connector fault in the actuator or solenoid circuit, such as high resistance, corrosion or chafingpossible
• Faulty boost pressure or position sensor giving false readingspossible
• Engine control unit fault or outdated calibration, where a manufacturer update addresses itrare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting load, rpm and boost at the time the fault set. Fix any other boost, air flow or sensor codes first.
2. Visually inspect the boost control solenoid, actuator, vacuum lines, hoses and clamps for splits, looseness, oil contamination or damage.
3. Inspect the wiring and connectors to the actuator or solenoid and boost sensor for corrosion, chafing, bent pins and poor retention.
4. Compare requested and actual boost, and actuator position where supported, using live data during a safe road test or load test.
5. Run the actuator or solenoid output test with a scan tool and check that it moves smoothly, responds and returns to rest.
6. Smoke test or pressure test the intake and intercooler system to find boost leaks.
7. Check vacuum supply and actuator operation using the correct vacuum or pressure test equipment, following the manufacturer's procedure for that engine.
8. Measure the circuit's resistance, supply, ground and signal against specification, and check the sensor reading against known good values. Procedures vary by model and engine.

How to fix

• Replace the faulty boost control solenoid or actuator, and carry out any adaptation or learning procedure the manufacturer requires.
• Repair or replace leaking hoses, clamps, pipes or the intercooler.
• Renew split or blocked vacuum lines, or repair the vacuum supply fault.
• Free, clean or replace a seized wastegate or variable geometry mechanism, or replace the turbocharger if it is worn or damaged.
• Repair damaged wiring or connectors, or replace a faulty boost or position sensor.
• Apply a manufacturer calibration update only if a known software issue applies to the vehicle.

Can I keep driving?

Nearby codes

• P0045GenericTurbocharger/Supercharger Boost Control A Circuit/Open
• P0047GenericTurbocharger/Supercharger Boost Control A Circuit Low