P00AF
Turbocharger/Supercharger Boost Control A Module Performance.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 0
- AreaFuel and air metering, auxiliary emission controls
- AF
- FaultThe specific fault in that area
What it means
P00AF is the generic SAE J2012 code for a performance fault in the Turbocharger/Supercharger Boost Control 'A' module. The engine control unit has detected that the boost control module or actuator is not responding or performing as commanded, or that its internal checks or feedback do not match what was requested. How the module is built and how it is checked varies by model and engine, so confirm the details for the specific vehicle.
Symptoms
- Engine warning light on
- Loss of power or poor acceleration
- Limp mode or reduced boost
- Turbo not building boost, or boost that is erratic
- Hesitation under load
- Possible whistling, fluttering or rattling noises from the turbo area
Possible causes
- Faulty or sticking boost control actuator (electronic wastegate or variable geometry vanes)likely
- Wiring or connector faults in the actuator circuit, such as corrosion, chafing, loose pins or high resistancelikely
- Carbon build-up or mechanical seizure in the turbo wastegate or vane mechanism, or a loose or damaged linkagelikely
- Boost leaks or vacuum supply faults on systems with a vacuum-operated actuatorpossible
- Low or unstable supply voltage, or poor earth connections affecting the modulepossible
- Faulty boost pressure or position sensor giving feedback that does not match the commandpossible
- Internal fault in the engine control unit or boost control module, or outdated softwarerare
How to diagnose
- Read all stored and pending codes and the freeze frame data, noting load, rpm and boost at the time the fault set. Check for related codes such as boost pressure, sensor or voltage faults.
- Check the battery condition and charging voltage, and inspect the main earths, as low voltage can cause module performance faults.
- Visually inspect the actuator, linkage, wiring and connectors for damage, heat, oil, corrosion or loose fittings.
- Inspect the intake and charge air pipework, clamps, intercooler and hoses for splits and leaks, and check any vacuum lines and pump on vacuum-operated systems.
- With the engine off, check by hand that the wastegate or vane linkage moves freely without binding, following the model's procedure.
- Use a scan tool to view live data and command the actuator, comparing commanded and actual position or boost, and watch for lag or no response.
- Test the actuator circuit supply, earth, signal and resistance against the manufacturer's data, and check the related sensors.
- Check for available software updates or technical bulletins for the engine, and confirm whether an update applies to the fault.
How to fix
- Repair or replace damaged wiring, terminals or connectors in the actuator circuit.
- Replace the boost control actuator if it fails testing, and carry out any required adaptation or calibration procedure for that model.
- Free off or clean a sticking mechanism where the manufacturer allows it, or replace the turbocharger if the wastegate or vanes are seized or worn.
- Repair boost leaks, split hoses or vacuum supply faults.
- Replace a faulty boost pressure or position sensor, and correct charging or earth faults.
- Update the engine control unit software if an outdated calibration is a known cause, or replace the unit only after all other causes are ruled out.
Can I keep driving?
The car may be driven carefully for a short time, usually in reduced-power mode, but have it checked soon. Continued driving with a faulty boost control can worsen the problem and may stress the engine or turbo, so avoid heavy loads and stop if power drops sharply or unusual noises occur.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.