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P0299: Turbocharger or supercharger underboost

The turbo is not reaching the boost the ECU asks for, so the car feels flat. The usual culprit is a leaking hose or a boost control fault.

Code P0299 at a glance
CodeP0299
SystemEngine and transmission
GroupP02xx, Fuel and injectors
TypeGeneric: it means the same on every make
Can you keep driving?With care

What P0299 means

The turbo (or supercharger) forces air into the engine so it makes more power. The ECU compares the boost it asks for with what the sensor measures, and here the actual pressure has fallen well short. To protect itself, the engine usually goes into limp mode.

Most common causes

  • Turbo or intercooler hose loose, split or with a slack clip
  • Broken or disconnected vacuum hose to the turbo actuator
  • Badly clogged air filter
  • Wastegate or variable vane mechanism sticking or out of adjustment
  • Faulty boost control solenoid or boost pressure sensor
  • Worn turbo with shaft play or oil leaks

Symptoms

  • Engine warning light on
  • Lack of power, especially on hills and when overtaking
  • Limp mode with limited power
  • Unusual whistle or whooshing when accelerating
  • Black smoke on diesels

Can you drive with P0299?

With care You can drive carefully, but with less power than normal, which matters when joining traffic or overtaking. If the turbo is leaking oil or making metallic noises, stop using the car.

How to check it

With the engine cold, run your hand along the large hoses between the turbo, intercooler and intake looking for oil residue, cracks or loose clips. With the reader, compare requested and actual boost live while accelerating in a high gear.

How to read and clear P0299 with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0299 with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

P0299 is a generic code, so it means the same on any make, for example on Audi, Fiat, Kia, Mazda, Opel / Vauxhall, Toyota. See what Final OBD does on your car in makes and models.

What does code P0299 mean?

The turbo (or supercharger) forces air into the engine so it makes more power. The ECU compares the boost it asks for with what the sensor measures, and here the actual pressure has fallen well short. To protect itself, the engine usually goes into limp mode.

Can you drive with P0299?

You can drive carefully, but with less power than normal, which matters when joining traffic or overtaking. If the turbo is leaking oil or making metallic noises, stop using the car.

How do you clear P0299?

With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0299 comes back.