Boost generation and regulation
Underboost can arise from charge-air leaks, actuator or wastegate control, diverter valve faults, pressure sensors, exhaust restrictions or turbocharger wear. An engine controller may also reduce requested boost because of unrelated fuel, ignition or temperature faults.
How a technician distinguishes possible causes
Compare requested and actual boost under the failure conditions. Pressure-test charge plumbing within specified limits, check actuator movement and sensor plausibility, and inspect intake and exhaust connections. Avoid condemning a turbocharger from a single underboost code.
Repair and post-repair verification
Repair the measured fault and confirm boost response and temperature control under a safe load test.
On applicable turbocharged 718 variants, reduced power can come from boost plumbing, sensors, controls or turbo hardware.
If you are experiencing this issue, contact Mich’s Foreign Cars in Hickory, NC at 828-324-6012. Provide the model, year, engine, warning text and when the symptoms occur so the service team can discuss an appropriate diagnostic visit.