When the code is set
The ECM uses the boost pressure sensor to compare the actual pressure in the intake with the requested pressure. If the actual pressure stays noticeably below the requested value for a few seconds, it stores P0299.
Can I keep driving?
Have it checked soon
A car in limp mode will usually still drive, but with less power. Drive gently and only as far as a garage, because driving with a faulty turbo can damage the engine. If you hear a loud whine from the turbo or the oil pressure warning light comes on, stop.
Symptoms
- The check engine light is on.
- Noticeably less power and slow acceleration.
- Limp mode: the engine will not pull above a certain engine speed.
- Hissing or whistling from the engine bay when accelerating.
Common causes
- A leak in the charge air system: a cracked hose, a joint or the intercooler.
- A faulty boost pressure sensor.
- A sticking wastegate or boost control fault.
- A fault in the EGR system.
- Low oil pressure, so the turbo is not properly lubricated.
- A faulty turbocharger.
How to find the cause
A mechanic usually works like this:
- Read all codes and freeze frame data.
- Inspect the charge air hoses and joints; a leak can often be heard while someone raises the revs.
- Compare actual and requested boost pressure on a test drive.
- Check that the wastegate or the turbo’s variable vanes move freely, and check how they are controlled.
- Check the oil pressure and the condition of the turbo.
Other ways the code is written
Scan tools and workshop printouts sometimes show the code with extra characters:
- P029900
Related codes
Frequently asked questions
Evoca fault code diagnostics is an informational aid and does not replace a professional inspection of your vehicle. Only an inspection of the vehicle at a workshop can confirm the cause of a fault.
Check P0299 for your car
Enter the code and, if you like, your car details. You get a free report with possible causes and next steps by email.