P0049
Turbocharger/Supercharger A Turbine Overspeed.
- Generic
- Powertrain
- Generic code
- High severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 0
- AreaFuel and air metering, auxiliary emission controls
- 49
- FaultThe specific fault in that area
What it means
P0049 means the engine control unit has detected that the turbine of turbocharger or supercharger 'A' has been spinning faster than its calculated safe limit. The speed is usually inferred from a turbo speed sensor or from boost pressure compared with what was commanded. The exact way overspeed is calculated depends on the engine and turbo design.
Symptoms
- Engine warning light on
- Engine goes into limp mode with reduced power
- Boost pressure surges or overboost
- Whistling, siren or unusual turbo noise
- Loss of performance or erratic power delivery
- Possible smoke from the exhaust
Possible causes
- Variable geometry vanes or wastegate stuck closed or slow to open, so boost and turbine speed climb too highlikely
- Faulty boost control actuator, solenoid or position sensor giving wrong feedback or movementlikely
- Vacuum or pressure line to the actuator split, disconnected or leaking, or a fault in the actuator's supplypossible
- Faulty turbo speed sensor or boost pressure sensor sending inaccurate readings, or wiring and connector faultspossible
- Soot or carbon build-up in the turbo or exhaust restriction affecting turbine controlpossible
- Outdated or faulty engine control unit calibration, where a manufacturer notice confirms itrare
- Internal turbocharger damage or worn bearingsrare
How to diagnose
- Read all stored and pending codes and the freeze frame data, noting engine speed, load, boost and the conditions when the fault set
- Check for related codes such as boost control, boost pressure or turbo position faults, and look up any manufacturer service information for the model
- Visually inspect the turbo, actuator linkage, hoses, intercooler pipes and wiring for damage, leaks, loose connections or corrosion
- Check vacuum or pressure supply to the actuator and test the control solenoid for correct operation and resistance
- Use live data to compare commanded and actual boost, actuator position and turbo speed (if fitted) while revving or on a road test
- Command the actuator or vanes with a scan tool where supported and check they move smoothly through their full range without sticking
- Check the boost, turbo speed and position sensors for correct signal and supply voltage and compare them with the specification for the engine
- Inspect for exhaust restrictions and check the turbo for shaft play, oil leaks and damage if the fault persists
How to fix
- Free off, clean or replace the sticking vanes, wastegate or linkage as the model allows
- Replace a faulty boost control actuator, solenoid or position sensor and carry out any required adaptation
- Repair or replace split, leaking or disconnected vacuum or pressure lines
- Repair damaged wiring or connectors, or replace a faulty turbo speed or boost pressure sensor
- Rectify exhaust or intake restrictions that affect turbo control
- Replace the turbocharger if internal damage is found, and correct the cause such as oil supply problems, then clear the code and road test
Can I keep driving?
High severity
Avoid driving until the cause is found, as overspeeding can quickly damage the turbo and engine. If the car is in limp mode and you must move it, keep speed and load low and for as short a distance as possible.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.