P0299: Turbocharger / Supercharger "A" Underboost
TL;DR
P0299 = turbo/supercharger underboost (less boost than commanded). Severity: medium. Top causes: boost/charge-pipe leak (40%), wastegate/actuator fault (25%), intake restriction or split hose (20%), failing turbo (15%). Common on EcoBoost, TSI and other turbo engines.
Can I keep driving with P0299?
IF you have reduced power / limp mode → you can usually drive gently to get it diagnosed, but performance will be poor. IF it’s also making boost-leak hissing or a clear turbo problem → minimize driving and fix it, as a failing turbo can worsen.
Symptoms
- Check engine light on
- Noticeable loss of power
- Reduced-power / limp mode
- Hissing or whistling under acceleration (boost leak)
- Sluggish acceleration, especially under load
Top causes (ranked by probability)
| Likely cause | Probability | Notes |
|---|---|---|
| Boost / charge-pipe leak (hoses, intercooler, clamps) | 40% | Most common — smoke-test the pressure side |
| Stuck or faulty wastegate / actuator / solenoid | 25% | |
| Restricted air filter or intake | 20% | |
| Failing turbocharger | 15% |
What does P0299 mean?
Technical explanation
The ECM commands a boost target and monitors actual manifold/boost pressure. P0299 sets when actual boost falls short of commanded by more than the allowed margin. The most common cause is a leak in the pressurised side (charge pipe, intercooler hose, clamps), which lets boost escape. A wastegate stuck open, a faulty wastegate actuator or solenoid, a restricted air filter/intake, or a worn turbo can also cause underboost. The car often enters reduced-power (limp) mode to protect the engine.
In simple terms
A turbo packs extra air into the engine for more power. P0299 means the engine isn’t getting as much of that boost as it should — usually because a pipe or hose on the pressure side is leaking, or a valve (wastegate) is stuck. The car feels gutless and may go into limp mode.
How to diagnose P0299 (step by step)
- Read commanded vs actual boost. Live data confirms boost is falling short of target.
- Pressure/smoke-test the charge system. Find leaks in charge pipes, intercooler and hose clamps.
- Inspect the wastegate and actuator. Check the wastegate moves freely and the actuator/solenoid works.
- Check the air filter and intake. Rule out a restriction on the inlet side.
- Assess the turbo. If no leaks or wastegate fault, inspect the turbo for wear.
Repair options & cost
- Repair the boost/charge-pipe leak
- Replace the wastegate actuator/solenoid or free a stuck wastegate
- Replace a restricted air filter
- Replace the turbocharger (advanced)
| DIY cost | $10–$600 |
|---|---|
| Workshop cost | $120–$2,500 |
| Repair time | 30 minutes (hose) to a day (turbo) |
Costs are local ballpark ranges and vary by region and vehicle.
Tools you’ll need
Scan your car: recommended OBD-II scanners →Vehicle-specific notes
- Very common on turbo engines — Ford EcoBoost, VW/Audi TSI, Hyundai/Kia turbo, etc.
- A popped-off or split charge pipe/intercooler hose is the most frequent cause — check clamps first.
- P0299 often appears with reduced-power mode; clearing the code without fixing the leak won’t last.
Common mistakes to avoid
- Replacing the turbo before finding a simple boost leak
- Overlooking loose or popped charge-pipe clamps
- Ignoring the wastegate actuator/solenoid
- Not smoke-testing the pressure side
Frequently asked questions
What does P0299 mean?
It means the turbo or supercharger is producing less boost than the computer commanded (underboost). The most common cause is a leak in the pressurised charge pipes/hoses, but a stuck wastegate, intake restriction or failing turbo can also cause it.
Can I drive with P0299?
Usually yes, gently — the car is often in reduced-power mode. Performance will be poor. If there’s a clear turbo problem, minimize driving and repair it.
Is P0299 expensive to fix?
It depends: a leaking hose or clamp is cheap, a wastegate actuator is moderate, and a failing turbocharger is the expensive case. Always find the leak first.
P0299 summary
| Meaning | Turbo/supercharger underboost |
|---|---|
| Severity | Medium |
| Safe to drive? | Caution — likely limp mode |
| Top cause | Boost / charge-pipe leak (40%) |
| DIY cost | $10–$600 |
| Shop cost | $120–$2,500 |