Wastegate
Definition
The wastegate is a valve that lets part of the exhaust bypass the turbine wheel once target boost is reached, preventing overboost and engine damage. Internal wastegates are a flap in the turbine housing moved by a diaphragm actuator or electric motor; the ECU modulates a solenoid (e.g. VAG N75) that regulates vacuum or pressure to the actuator. A seized flap, stretched actuator rod, cracked diaphragm or split vacuum hose causes either underboost (flap stuck open) or dangerous overboost (flap stuck closed), and electric actuators lose their learned end stops. Rattling at idle often points to a worn wastegate pivot bushing rather than the turbo itself. Codes: P0243-P0250 (wastegate solenoid), P0234 overboost, P0299 underboost, P0035 (bypass valve A).
Codes often stored
- P0035Turbo Charger Bypass Valve Control Circuit High
- P0234Turbocharger/Supercharger 'A' Overboost Condition
- P0243Turbo/Super Charger Wastegate Solenoid 'A'
- P0245Turbo/Super Charger Wastegate Solenoid 'A' Low
- P0246Turbo/Super Charger Wastegate Solenoid 'A' High
- P0299Turbocharger/Supercharger 'A' Underboost Condition