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 |
|---|---|
| System | Engine and transmission |
| Group | P02xx, Fuel and injectors |
| Type | Generic: 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.
Open the bonnetthe in-depth explanation
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 its description and whether it’s confirmed, pending or permanent.
If the engine stores it over standard OBD, with FREE you read this code with its explanation for nothing and clear it. With PRO you also read the faults of every control unit and clear them in all of them.
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 an inspection. It’s all in how to read and clear fault codes and in inspections and OBD.
Similar codes
- P0295 The cylinder 12 injector gives a higher signal than normal
- P0296 Cylinder 12 contributes unevenly to engine power
- P0297 The car has gone over its programmed top speed
- P0298 The engine oil is getting too hot
- P029A The cylinder 1 mixture correction has reached its upper limit
- P029B The cylinder 1 mixture correction has reached its lower limit
- P029C The cylinder 1 injector is clogged
- P029D There is a leak in the cylinder 1 injector
- P0200 Injector circuit malfunction
- P0201 Injector circuit malfunction, cylinder 1
- P0202 Injector circuit malfunction, cylinder 2
- P0203 Injector circuit malfunction, cylinder 3
To understand it properly
We explain how that system works, with drawings and no waffle, in our mechanics guide: Turbo and intercooler.
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.
Read it on your car
Final OBD reads and clears engine faults through standard OBD for free, each one explained in plain English. With PRO it also reads the faults of every control unit, each make’s own codes included, and clears them in all of them.
