Category: Powertrain → Turbo/Boost
What it means (plain English)
The PCM expected boost under load but didn’t detect adequate boost pressure, pointing to a mechanical/airflow problem (leaks, wastegate stuck open, VGT not moving) or signal problem. CarParts
Symptoms you’ll notice
- CEL, low power, may enter limp mode; drivability complaints under acceleration. YourMechanic
Priority level
High. Under-boost from mechanical failure can cause unsafe merging/towing performance and may cascade into DPF/EGR faults on diesels. CarParts
Common causes
- Charge-air leaks (intercooler/hoses/clamps) or intake restrictions.
- Wastegate stuck open/failed actuator/vacuum leaks.
- VGT mechanism stuck (soot/corrosion) → no vane movement.
- Faulty boost/MAP sensor or wiring (false “no boost”). CarParts+1
How pros diagnose it (step-by-step)
- Confirm with scan data: boost request vs actual. 2) Smoke/pressure test charge system. 3) Command/observe wastegate or VGT actuator movement. 4) Verify vacuum supply (if pneumatic). 5) Check MAP/boost sensor plausibility and wiring. CarParts+1
Likely fixes
- Seal boost leaks, replace split hoses/couplers/intercooler.
- Repair/replace actuator or wastegate, restore vacuum control.
- Free/repair VGT (clean/replace seized components).
- Replace faulty boost sensor/repair harness. YourMechanic
Related / companion codes
P0299 (underboost), P0243/P0245 (wastegate solenoid), P2563/P003A (VGT position). Kbb.com
Tech notes (quick hits)
On diesel platforms, a kinked inlet hose or soot-stuck VGT is a frequent real-world root cause discussed by techs. Cummins Forum