Fuel and air

P0049 — Turbocharger/Supercharger Turbine Overspeed

Severity: high Drive with care, to a shop

What P0049 means

The engine control module saw, from a turbine speed sensor or calculated boost data, that the turbine is spinning faster than allowed. Normally a wastegate or variable-geometry vanes limit boost, and the module compares target and actual boost pressure. When boost goes out of control, P0049 is stored.

Symptoms

  • Check Engine light on
  • Loss of power, possibly limp mode
  • No boost or erratic boost
  • Whining, whistling or rattling from the turbo
  • Smoky exhaust
  • Rough or hesitant acceleration

Possible causes

  1. Stuck or faulty wastegate or bypass valve actuator
  2. Faulty boost pressure or turbine speed sensor, or wiring problems
  3. Worn or damaged turbo (shaft play, damaged wheel)
  4. Leaking or disconnected boost control hoses and vacuum lines
  5. Faulty boost control solenoid
  6. Rarely, ECM software fault

How to diagnose

  1. Scan for codes and freeze frame data, and note any other boost-related codes
  2. Compare commanded and actual boost on live data
  3. Inspect wiring and connectors for the boost sensor and control valve
  4. Check vacuum lines and charge-air hoses for cracks and leaks
  5. Test wastegate or vane actuator movement over its full range, by hand and with a scan tool
  6. Check the turbo for shaft play, oil in the piping and wheel damage
  7. Check oil level and condition, and look for a clogged air filter or restricted exhaust

Common fixes

  • Repair or replace the wastegate actuator or bypass valve
  • Replace the boost or speed sensor and repair wiring
  • Replace hoses and fix leaks
  • Rebuild or replace the turbocharger
  • Update ECM software if the manufacturer offers it

Questions and answers

Can I drive with P0049?

Only to a nearby shop and under light load. Extended driving with faulty boost control can destroy the turbo and damage the engine.

What most often causes P0049?

Usually a sticking wastegate actuator or boost control valve, a bad pressure sensor, or a leaking hose. A worn turbo is less common but the most expensive.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.