Audi 90 EGR Control Solenoid Replacement at your home or office.

What is the EGR Control Solenoid all about?

Exhaust gas recirculation, or EGR, systems were developed to reduce engine emissions by reintroducing exhaust gas into the air/fuel mixture. This burns any remaining or partially burnt fuel in the exhaust and cools the combustion chamber, which produces fewer nitrous oxides. EGR systems have changed significantly, shifting from vacuum solenoid to electrically controlled systems. Modern EGR valves employ a solenoid that regulates the amount of exhaust that enters the intake process. Instead of being open and closed, the control solenoid ‘flutters’ rapidly, with the amount of open and closed times varying minutely with each flutter. When the engine temperature is cold, the EGR control solenoid allows little to no exhaust into the intake. While at wide open throttle, the solenoid is open nearly all the time.

When the EGR control solenoid doesn’t close during cold operation, the engine runs poorly or stalls. When the control solenoid doesn’t open properly, engine pinging or knocking is readily heard. In any situation of EGR control solenoid malfunction, the Check Engine light will come on.