P0299
Turbocharger or Supercharger Underboost Condition
Your engine is not making the boost pressure it should. This usually causes weak acceleration, poor power, and sometimes a check engine light with limp mode.
- SEV
- 4/5
- DRIVE
- CAUTION
- DIY
- $20–$350
- SHOP
- $150–$2,500+
Quick answer
AI-CITATION READYWhat it means
Can you drive with it?
Most common causes
- Boost leak from a cracked intercooler hose, loose clamp, split charge pipe, or leaking intercooler
- Faulty wastegate actuator, sticking wastegate, or boost control solenoid problem
- Vacuum line leak or damaged vacuum supply to turbo control components
Typical repair cost
DIY usually runs $20–$350. Typical shop repair lands around $150–$2,500+, depending on the root cause.
01 / Definition
P0299 sets when the powertrain control module sees actual boost pressure lower than the commanded or expected boost level for a certain time and operating condition. The fault can be caused by boost leaks, control system problems, sensor errors, exhaust flow issues, or a worn turbocharger/supercharger.
02 / Drive status
With caution. You can usually drive short distances gently, but power may be limited and the problem can get worse quickly. Avoid hard acceleration, towing, or highway merging until it is diagnosed.
03 / Symptoms
- Check engine light
- Poor acceleration
- Low engine power
- Limp mode
- Whistling or hissing from boost leak
- Black smoke under acceleration on some diesel engines
- Reduced fuel economy
- Engine may struggle at highway speeds or under load
04 / Causes
| 1 | Boost leak from a cracked intercooler hose, loose clamp, split charge pipe, or leaking intercooler | high |
|---|---|---|
| 2 | Faulty wastegate actuator, sticking wastegate, or boost control solenoid problem | high |
| 3 | Vacuum line leak or damaged vacuum supply to turbo control components | high |
| 4 | Worn or failing turbocharger with shaft play, damaged compressor wheel, or poor boost output | medium |
| 5 | Intake restriction such as a clogged air filter or collapsed intake duct | medium |
| 6 | Exhaust restriction or exhaust leak before the turbo reducing turbine energy | medium |
| 7 | Faulty MAP sensor, boost pressure sensor, or MAF sensor causing incorrect boost readings or control | medium |
| 8 | Diverter valve or bypass valve leaking boost pressure | medium |
| 9 | Low engine oil supply or oil contamination affecting turbo operation | low |
| 10 | PCM software issue or less common wiring/connectivity fault | low |
05 / Diagnostic sequence
- 01Scan for all stored and pending codes and review freeze frame data.
- 02Inspect intercooler pipes, charge hoses, clamps, and the intercooler for leaks, oil residue, cracks, or loose connections.
- 03Check all vacuum lines and boost control hoses for splits, disconnections, soft spots, or collapse.
- 04Inspect the wastegate actuator, linkage, boost control solenoid, and diverter or bypass valve for sticking or leakage.
- 05Monitor commanded boost versus actual boost with a scan tool during a controlled road test.
- 06Smoke test or pressure test the intake and charge air system to find hidden boost leaks.
- 07Inspect air filter and intake ducting for restriction or collapse.
- 08Check MAP, boost, and MAF sensor readings and compare them to known-good values at idle and under load.
- 09Inspect the turbocharger for shaft play, damaged fins, oil leakage, or signs of seizure.
- 10Check for exhaust leaks before the turbo and restrictions in the exhaust system if no intake-side fault is found.
06 / Repairs
| 1 | Repair or replace leaking boost hoses, charge pipes, clamps, or intercooler | $20–$600 |
|---|---|---|
| 2 | Replace damaged vacuum lines or reconnect loose control hoses | $10–$120 |
| 3 | Replace faulty boost control solenoid, wastegate actuator, or repair sticking wastegate linkage | $80–$600 |
| 4 | Replace leaking diverter valve or bypass valve | $75–$300 |
| 5 | Replace clogged air filter or damaged intake duct | $20–$150 |
| 6 | Replace faulty MAP, boost, or MAF sensor after testing confirms failure | $50–$350 |
| 7 | Repair exhaust leak ahead of the turbo or correct exhaust restriction | $100–$800 |
| 8 | Replace the turbocharger or supercharger if it is worn or damaged | $700–$2,500+ |
| 9 | Update PCM software or repair related wiring if all mechanical causes are ruled out | $100–$300 |
07 / Related codes
08 / FAQ
Can a boost leak cause P0299?
Yes. A leaking hose, cracked charge pipe, loose clamp, or leaking intercooler is one of the most common causes of P0299.
Will P0299 cause limp mode?
Yes. Many vehicles reduce power to protect the engine and turbo system when underboost is detected.
Can I keep driving with P0299?
Only cautiously and for short trips if the vehicle still runs normally enough to move safely. Continued driving can worsen turbo damage or leave you with very limited power.
Does P0299 always mean the turbo is bad?
No. Many P0299 cases are caused by leaks, bad vacuum lines, a faulty wastegate control system, or a sensor problem rather than a failed turbocharger.
What does underboost feel like?
The vehicle usually feels weak, slow to accelerate, and may struggle more than normal when climbing hills or merging onto the highway.
09 / Source and method
- DATA BASIS
- OBD-II REFERENCE + OBD2.HELP
- METHOD
- STATIC VALIDATION
- SAFETY
- INFORMATIONAL
This page combines OBD-II diagnostic reference data with OBD2.help generated diagnostic guidance for code meaning, likely causes, and repair direction.
Publishing uses deterministic schema and build validation, plus manual spot checks on representative pages before release.
Safety-critical diagnosis and repairs should be confirmed with a qualified mechanic, especially when the vehicle is misfiring, overheating, or losing power.