P0299 on Ford EcoBoost – Turbo Underboost

Platform‑specific notes for diagnosing underboost on Ford EcoBoost engines (Fiesta, Focus, Puma and similar).

Typical Symptoms on EcoBoost Platforms

  • Noticeable lack of power, especially at higher RPM or full throttle.
  • Slower than usual turbo spool‑up or boost that tapers off early.
  • Whistling, whooshing or hissing noises from the intercooler/boost pipework.

Common EcoBoost‑Specific Causes

  • Split intercooler hoses or loose clamps after service or hardware changes.
  • Cracks in plastic boost pipes or end tanks.
  • Wastegate actuator or control valve faults leading to low commanded boost.
  • Sticking turbo vanes on some diesel‑derived variants where applicable.
  • Software mismatches after mapping or incorrect actuator setup.

Suggested Test Plan

  1. Use live data to compare commanded boost vs. actual boost through a full‑throttle pull.
  2. Perform a careful visual and hands‑on inspection of all boost pipes and intercooler joints.
  3. Where possible, perform a smoke or pressure test of the charge‑air system.
  4. Check wastegate actuator movement with a hand vacuum/pressure pump where fitted.
  5. On mapped cars, confirm that the hardware (actuator, turbo, intercooler) matches the tune.