P0299 means the turbocharger (or supercharger) is producing less boost pressure than the engine computer is requesting, so the engine cannot make its expected power. The cause is often cheaper than a new turbo — a leaking boost hose or intercooler pipe, a loose clamp, a wastegate stuck open, or a faulty boost control solenoid — and the car commonly drops into limp mode to protect itself.
What Does P0299 Mean?
A turbocharger uses exhaust energy to push extra air into the engine. The computer sets a target boost pressure for every load and compares it with what the boost sensor reports. P0299 is stored when the real pressure stays below the target for long enough — in other words, the turbo is not building the boost it should.
Many things sit between the turbo and the engine, and a failure anywhere along the path produces the same code: leaks in the pipes, a valve that will not close, a sensor that reads wrongly, or a turbo that is worn out. Work from the simple and cheap towards the expensive. See also the car loses power when accelerating guide.
P0299 is a shortfall — less boost than requested. The opposite fault, boost above the target, has its own code. Do not mix up the two when reading an online forum thread: the causes are largely different.
Common Symptoms
- Check engine light on, with noticeably reduced power.
- Limp mode — see car stuck in limp mode.
- Weak acceleration, especially uphill — see car loses power uphill only.
- A whistling or hissing sound under load — a classic boost leak. See whistling noise from the engine.
- Blue smoke if the turbo itself is leaking oil — see blue smoke from exhaust.
Common Causes, Most Likely First
- A boost leak — a split or loose hose, a cracked intercooler pipe or a leaking clamp.
- A wastegate that is stuck open or an actuator that has failed or lost its vacuum.
- A faulty boost control solenoid or a cracked vacuum line to the actuator.
- A leaking diverter or blow-off valve.
- A restricted air filter or intake — see our air filter guide.
- An exhaust restriction, such as a clogged catalytic converter — see P0420.
- A worn or damaged turbo, including a sticking variable-vane mechanism on some designs.
- A wrong boost or air-flow sensor reading — see P0101.
How to Diagnose It
- Look and listen for leaks. Check every hose and clamp between the turbo, intercooler and throttle body for splits, oil film or loose fittings. Oil residue around a joint is a giveaway.
- Check the air filter and intake for blockage.
- Inspect the wastegate actuator rod and vacuum lines. The rod should move freely.
- Read live boost data with a scan tool during a safe, legal drive and compare actual boost with the target — see the OBD-II scanner guide.
- Have a shop pressure-test the intake tract to find leaks you cannot see.
- Check for a clogged exhaust or catalytic converter if everything else looks sound.
Let the engine and exhaust cool before touching hoses, sensors or connectors, and never open a hot cooling system. Keep hands, hair and loose clothing away from belts and fans, which can start without warning.
Possible Fixes
| Cause | Fix | Typical cost |
|---|---|---|
| Loose clamp or split hose | Tighten or replace the hose | $20 – $300 |
| Cracked intercooler or pipe | Replace the part | $150 – $900 |
| Boost control solenoid or vacuum line | Replace the solenoid or line | $80 – $400 |
| Stuck wastegate or actuator | Free or replace the actuator | $200 – $800 |
| Clogged exhaust or catalytic converter | Replace the restricted part | $500 – $2,500 |
| Failing turbocharger | Rebuild or replace the turbo | $1,200 – $3,500 |
Can I Drive With P0299?
Short trips only, and gently. Limp mode is the car protecting itself, but a boost problem left alone can become expensive: a leaking oil seal can damage the catalytic converter, and a restricted exhaust can overheat the turbo. If the light is flashing or you hear grinding or a loud whine, stop — see our flashing check engine light guide.
When to See a Mechanic
If a visual check finds nothing, or a new hose and clamp do not clear the code. Ask for a smoke or pressure test of the intake. More in our engine section.
Frequently Asked Questions
What does P0299 mean?
The turbocharger is delivering less boost pressure than the engine computer is requesting, so the engine cannot make its expected power.
What is the most common cause of P0299?
A boost leak — a split hose, cracked intercooler pipe or loose clamp — is the most common and the cheapest cause to find.
Is P0299 the same as a failed turbo?
Not necessarily. Leaks, a stuck wastegate, a bad solenoid or a restricted exhaust can all cause it before the turbo itself is at fault.
Why does my car go into limp mode with P0299?
The computer limits power to protect the engine and turbo when boost does not match its target.
How much does it cost to fix P0299?
From about $20 for a clamp or hose up to $1,200–$3,500 for a turbocharger replacement.
