P0248
Turbocharger/Supercharger Wastegate Actuator B Range/Performance.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 2
- AreaFuel and air metering (injector circuit)
- 48
- FaultThe specific fault in that area
What it means
P0248 is the generic code for a range or performance fault on the turbocharger or supercharger wastegate actuator 'B', which is normally the second wastegate control circuit or actuator on engines that have more than one. The engine control unit has seen the actual boost or wastegate position differ from its commanded target by more than an allowed amount for a set time. Which turbo or bank 'B' refers to depends on the model and engine.
Symptoms
- Engine warning light on
- Loss of power or poor acceleration, often with the engine in limp mode
- Boost pressure too low or, on some engines, overboost
- Whistling, hissing or rattling from the turbo area
- Uneven power delivery between banks on twin-turbo engines
- Increased fuel consumption
Possible causes
- Wastegate actuator sticking, seized or worn linkage, or corroded or carbon-fouled wastegate flaplikely
- Vacuum leak or split hose to a vacuum-operated actuator, or a faulty vacuum solenoid or control valvelikely
- Wiring or connector fault in the actuator circuit, such as chafing, corrosion or high resistance (electric actuators)possible
- Boost leak in the charge-air system, such as a split pipe, loose clamp or leaking intercoolerpossible
- Faulty boost pressure sensor or position feedback sensor giving inaccurate readingspossible
- Failed electric actuator motor or internal electronicspossible
- Damaged turbocharger or exhaust leak upstream of the turbine affecting boost controlrare
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 boost or turbo codes.
- Visually inspect the wastegate actuator, its linkage, vacuum hoses and wiring connectors for damage, disconnection, chafing or heat damage.
- Check the charge-air system for leaks, including pipes, clamps and the intercooler, ideally with a pressure test.
- Check the vacuum supply and the control solenoid on vacuum-operated systems, following the manufacturer's procedure for your model.
- With a scan tool, compare commanded and actual boost and actuator position, and run any actuator test available. Check that the actuator moves smoothly through its full range.
- Test the actuator circuit for supply, earth, signal and resistance against the manufacturer's specification.
- Check the boost and position sensor readings for plausibility against known values at idle and under load.
- Inspect the wastegate flap and turbo for free movement and wear, as far as the engine design allows. Procedure varies by model.
How to fix
- Free off or replace a stuck or worn wastegate actuator or linkage, and address any flap fouling as the manufacturer advises.
- Replace split vacuum hoses or a faulty control solenoid or valve.
- Repair damaged wiring or connectors in the actuator circuit.
- Repair boost leaks by replacing the damaged pipes, seals or clamps.
- Replace a faulty boost or position sensor, then clear the codes and confirm by road test.
- Replace the turbocharger if it is damaged or if the wastegate is integral and cannot be repaired. Perform any actuator adaptation or calibration the manufacturer requires.
Can I keep driving?
The car can usually be driven gently over a short distance, as it will often be in limp mode with reduced power. Get it checked soon, because an overboost condition or a damaged turbo could cause engine damage.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.