P0299: Turbocharger or Supercharger Underboost
The engine is not getting the boost pressure it asked for.
Severity: 2 of 4
Drive gently to a shop. Many vehicles go into reduced power mode, which can be unsafe when merging. If you see blue smoke, hear grinding from the turbo, or the oil warning comes on, park it, because turbo failure can damage the engine.
Estimate range covers the repairs listed below; see the cost breakdown. A flashing check engine light, a hot temperature gauge, or brakes that feel different mean stop driving and get help.
What P0299 means
On turbocharged or supercharged engines, the computer requests a certain boost pressure and measures what it gets. P0299 means actual boost is lower than expected.
Leaks in intake piping are common causes. Turbo failure is possible but should be confirmed.
Boost is measured by a pressure sensor in the intake. The computer compares that reading with the boost it requested for the current throttle and engine load. A small shortfall for a moment is normal; P0299 sets when the gap is large or lasts too long.
Most turbo systems use a wastegate to limit boost. If the wastegate sticks open, exhaust bypasses the turbine and the turbo cannot spin fast enough. Many newer engines use an electronic wastegate actuator that can fail electrically or mechanically.
Superchargers are driven by a belt, so a slipping belt or failing bypass valve can also cause underboost.
Common causes (cheapest likely first)
- Boost leak in intercooler hoses or clamps. Common and inexpensive.
- Wastegate or actuator problem. Can stick open.
- Boost sensor or control valve fault. Wrong readings or control.
- Clogged air filter. Restricts flow.
- Worn turbocharger. Costly; confirm first.
Symptoms
- Loss of power
- Limp mode
- Whistling or hissing
- Possible smoke
- Black smoke under acceleration on some engines
- Oil residue on charge pipes
DIY difficulty: Moderate to hard
Checking clamps and hoses is easy. Turbo replacement is advanced.
Tools: OBD-II scanner with boost data, Hose clamp tools, Boost leak tester
How to check for a boost leak
- With the engine cool, inspect each charge pipe, coupler, and clamp between the turbo, intercooler, and throttle body. Look for oil film, cracks, or loose clamps.
- Shops use a boost leak tester that pressurizes the intake to a safe level so leaks can be heard and felt.
- Use scan data to compare requested and actual boost during a safe, legal acceleration test.
- If the system holds pressure, move on to the wastegate actuator and boost control valve.
Estimated repair cost
This is an estimate, built from typical parts price ranges plus labor hours times an assumed shop rate of $110 to $190 per hour. Actual prices vary by vehicle, region, and shop. Diagnosis fees are often extra.
| Repair | Parts | Labor | Estimate (low / high) |
|---|---|---|---|
| Intercooler hose or clamp | $20 to $200 | 0.5 to 2.0 h | $20 + 0.5 × $110 = $75 $200 + 2.0 × $190 = $580 |
| Boost control valve | $40 to $250 | 0.5 to 1.5 h | $40 + 0.5 × $110 = $95 $250 + 1.5 × $190 = $535 |
| Turbocharger | $600 to $2,500 | 3.0 to 8.0 h | $600 + 3.0 × $110 = $930 $2,500 + 8.0 × $190 = $4,020 |
Watch a repair video
Search YouTube for “P0299 fix” videos. Pick a recent video that matches your engine, and confirm the diagnosis before buying parts.
P0299 by make
Brand specific notes: Ford, Volkswagen, BMW, Chevrolet. Other makes: the code works the same way; see all makes.
Repair manuals
Step-by-step service manuals with torque specs and wiring diagrams:
Haynes manuals Chilton manuals
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Related codes
Check for recalls
Before paying for a repair, enter your VIN in the NHTSA recall lookup. Emissions parts may also be covered by a federal emissions warranty; check your warranty booklet.
FAQ
Can I drive with P0299?
Short distances, gently. Watch for oil warnings or smoke.
Is it always the turbo?
No. Boost leaks and controls are frequently the cause.
What does a boost leak sound like?
Often a hiss or whistle under acceleration that was not there before. Large leaks can sound like a whoosh, and power drops noticeably.
Can low oil pressure cause P0299?
Turbos rely on engine oil. Oil starvation damages turbo bearings and can lead to underboost. Keep up with oil changes using the specified oil.
Will a bigger air filter fix P0299?
No. A clogged filter can contribute, but a performance filter will not fix a leak or a wastegate problem.