Turbo & Intake

P0299Turbocharger/Supercharger A Underboost Condition

High RiskDifficulty:Moderate1-5 hours
Is it safe to drive?
Short trips, with care

The car goes into limp mode and cuts power. If the cause is a lubrication problem or shaft play in the turbo, the turbo can disintegrate completely if you keep driving.

Will it pass inspection?
Risky

Low boost can produce heavy smoke on diesels and cause problems in the opacity test.

01 / 06

What does P0299 mean?

The turbo can't produce the pressure the ECU asks for. Before saying 'the turbo is dead', know this: most of the time the cause is a cracked intercooler hose, a loose clamp or the vacuum line that drives the turbo actuator. Replacing the turbo is the last step.

P0299 is stored when the value measured by the intake manifold pressure (MAP/boost) sensor stays below target boost for a certain time. Boost leaks, variable geometry turbo (VGT) vanes stuck with soot, and actuator or vacuum solenoid faults are the most common causes.

02 / 06

How to fix P0299

Steps are ordered from cheapest to most expensive. If a step doesn't solve it, move to the next one, and don't let a garage replace parts blindly.

  1. 1

    Hose and clamp check

    DIY

    Inspect every hose from the turbo outlet to the throttle body, and the intercooler, for oil residue/cracks. A pressure test gives the clearest result.

  2. 2

    Vacuum line and solenoid test

    Pro job

    Test the vacuum hoses to the turbo actuator and the control solenoid with a vacuum pump.

  3. 3

    Actuator movement test

    Pro job

    Actuate it with diagnostics and confirm the rod moves freely.

  4. 4

    VGT cleaning

    Pro job

    Additives without removing the turbo are of limited use; the permanent fix is removing the turbo and cleaning the vane mechanism.

  5. 5

    Turbo rebuild / replacement

    Pro job

    Done if there is shaft play or wheel damage. Before replacement, always check the oil feed line and the DPF.

Don't replace these first

  • Turbo (without testing the hoses)
  • MAP sensor

These parts are often replaced unnecessarily for P0299. Don't spend money on them before doing the checks above.

03 / 06

P0299 symptoms

  • Noticeable loss of power, limp mode
  • Whistling or blowing sound from the turbo
  • Black smoke
  • No pulling power uphill
  • Check engine light

04 / 06

What causes P0299?

  • Cracked intercooler / turbo hose or loose clampVery high
  • VGT vanes stuck with sootHigh
  • Faulty turbo actuator / vacuum solenoidMedium
  • Exhaust back pressure from a clogged DPF or EGRMedium
  • Turbo shaft play / damaged compressor wheelLow

05 / 06

Which cars commonly get P0299?

06 / 06

Frequently asked questions

What does fault code P0299 mean?

P0299 stands for “Turbocharger/Supercharger A Underboost Condition”. The turbo can't produce the pressure the ECU asks for. Before saying 'the turbo is dead', know this: most of the time the cause is a cracked intercooler hose, a loose clamp or the vacuum line that drives the turbo actuator. Replacing the turbo is the last step.

Can I drive with code P0299?

Short trips, with care. The car goes into limp mode and cuts power. If the cause is a lubrication problem or shaft play in the turbo, the turbo can disintegrate completely if you keep driving.

Will a car with code P0299 pass vehicle inspection?

Risky. Low boost can produce heavy smoke on diesels and cause problems in the opacity test.

Does the turbo need replacing for P0299?

Usually not. Most cases are hose leaks, the actuator or sooted VGT vanes. Replace the turbo only after ruling out the other causes.

Related codes

P0101P0401P2002