Check Engine Code
P0299
Turbocharger / Supercharger "A" Underboost
What P0299 means
P0299 sets when actual boost is consistently lower than commanded. Common on Ecoboost, Hyundai/Kia turbo, VAG TSI/TFSI engines.
Symptoms
- Check engine light
- Significant power loss
- Limp mode when boost drops far below target
- Hissing sound under load (boost leak)
- Slow turbo spool
Likely causes (most common first)
- Boost leak — split intercooler hose, cracked charge pipe (most common)
- Failed wastegate actuator (stuck open)
- Failed turbo (worn vanes / shaft play)
- Stuck blow-off valve / diverter valve
- Restricted air filter
- Failed boost pressure sensor
Can I keep driving?
Medium — drivable but fix soon
Typical repair cost
DIY fixes can start near $30 (parts only). Shop repairs for P0299 typically run up to $2500 depending on the underlying cause and vehicle. Start with the most common cause — Boost leak — split intercooler hose, cracked charge pipe (most common) — before throwing parts at it.
Symptoms that match P0299
If you got here from a search query, one of these might describe what your car is actually doing:
Related codes
Confirm P0299 yourself in 60 seconds
AXLY.pro is a free iPhone app that pairs with any Bluetooth OBD2 adapter to read P0299 and every other stored code, plus live engine data. No subscription.