P0248

Turbocharger Wastegate Solenoid B Range/Performance

P0248 is a generic OBD-II powertrain diagnostic trouble code: Turbocharger Wastegate Solenoid B Range/Performance. It is logged by the engine control unit when the turbo/boost monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P0248
Group
Powertrain
System
Turbo/Boost
Severity
Warning (MIL on, possible limp mode)
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What P0248 means

P0248 indicates that the PCM has confirmed wastegate solenoid B is electrically functional but the resulting boost pressure or actuator position response falls outside the expected performance range. Unlike P0247 (a broad malfunction flag that includes circuit faults) or P0249 (a circuit-low voltage fault), P0248 is a rationality or range/performance code — meaning the solenoid receives its commands correctly but the physical wastegate response does not match the commanded position or expected boost outcome.

Common mechanical causes include a seized or heavily carboned wastegate valve that cannot move freely despite solenoid activation, a torn actuator diaphragm that cannot build sufficient differential pressure to move the valve, or a bent actuator rod that mechanically prevents travel. On electronic actuator platforms (Audi 4.0T and newer Continental/Bosch e-wastegate systems), a worn motor or failed position sensor inside the actuator can also trigger P0248 if the PCM compares commanded position against feedback and finds a mismatch.

Diagnosis should progress from a live data review of commanded versus actual boost pressure, through a physical inspection of the actuator rod travel, to a vacuum pump or activation test of the actuator itself. Software-related causes — an outdated ECU calibration that sets the performance window too tightly — are rare but have been documented on some Ford EcoBoost and Mercedes-Benz platforms after reflashing. The engine will typically enter a protective boost-limited mode while P0248 is active.

Common causes

Most-frequently reported root causes when P0248 is logged.

  • 1
    Seized, corroded, or heavily carbon-fouled wastegate B valve preventing mechanical movement despite correct solenoid operation.
  • 2
    Torn, cracked, or leaking wastegate actuator B diaphragm reducing the pressure force available to open or close the valve.
  • 3
    Bent, disconnected, or jammed actuator rod preventing full travel of the wastegate flap.
  • 4
    Worn electric motor or failed position feedback sensor inside an electronic (e-actuator) wastegate B unit.
  • 5
    Vacuum or boost pressure supply hose to the actuator cracked or disconnected, reducing actuation authority.
  • 6
    High-resistance wiring or connector issue causing marginal solenoid energisation that passes electrical tests but cannot develop full solenoid force.
  • 7
    Outdated or corrupted ECU calibration with an incorrectly narrow boost-response performance window triggering a false rationality fault.

Symptoms drivers notice

MIL illuminated with P0248 stored.
Boost pressure lower than target under load, measured via live scan data.
Engine enters protective limp mode capping boost to prevent overboost or uncontrolled pressure.
Sluggish acceleration particularly above 3,000 RPM where full boost is expected.
Possible companion overboost or underboost codes if the wastegate is stuck at an extreme position.
Audible mechanical rattle or resistance when physically checking actuator rod movement by hand with engine off.

How to diagnose P0248

A typical diagnostic flow when this code is present.

  1. 1
    Connect a scan tool and compare commanded versus actual boost pressure in live data while an assistant performs a wide-open-throttle pull — a mismatch confirms a performance/rationality fault.
  2. 2
    Visually inspect the wastegate B actuator rod end, pivot, and linkage for bending, seizure, or physical damage with the engine cold.
  3. 3
    Attempt to manually move the actuator rod through its full travel by hand; heavy resistance or inability to move indicates a seized valve or bent rod.
  4. 4
    Apply vacuum (or boost pressure as specified) to the actuator with a hand pump while observing rod travel — a torn diaphragm will not hold pressure and the rod will not move.
  5. 5
    On electronic actuator platforms, command the actuator through its full range via the scan tool's actuator test function and observe whether it reaches both end stops.
  6. 6
    Inspect all vacuum and pressure hoses connected to the solenoid and actuator for cracks, splits, or loose clamps.
  7. 7
    If the wastegate valve itself is seized due to carbon build-up, a walnut-blast or chemical clean of the turbine housing area may restore movement before replacing the actuator assembly.

Related powertrain codes

Frequently asked questions

How does P0248 differ from P0247?

P0247 is a generic malfunction flag that includes electrical faults and may set even if the solenoid circuit has an open or short. P0248 is a rationality code — the PCM has confirmed the solenoid circuit is electrically intact but the wastegate's physical response (boost pressure or position) does not match what was commanded. P0248 points more specifically to mechanical or actuator-level failures.

Can a software update fix P0248?

On some platforms — particularly certain Ford EcoBoost and Mercedes-Benz models — an overly tight boost performance window in the ECU calibration has been the root cause. Checking for available PCM software updates before replacing mechanical components is a low-cost first step, especially if the code appears after an ECU reflash.

Is a seized wastegate dangerous?

If the wastegate is seized open, boost will be chronically low and the turbo may overspool as exhaust energy is wasted. If seized closed, overboost can occur, risking detonation and engine damage. Either condition requires prompt attention.

Does P0248 require wastegate replacement, or can the valve be freed?

Depending on the degree of carbon build-up or corrosion, it is sometimes possible to free a stuck wastegate by chemical cleaning or walnut blasting without full turbo removal. If the actuator diaphragm is torn or an e-actuator motor has failed, replacement of the actuator or turbocharger assembly is necessary.

Disabling P0248 in software

RaceTune can permanently disable P0248 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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