Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
EGR System - Gasoline: Description
The exhaust gas recirculation (EGR) system, used on vehicles with gasoline engines, is designed to reduce emissions of oxides of nitrogen (NOx).
This process is accomplished by lowering combustion temperatures of burning gases. Recirculated and metered amounts of exhaust gases are reintroduced into the engine through the intake manifold where they are mixed with the air/fuel mixture.
On some models, the vacuum signal to the EGR valve is controlled by an ECM controlled solenoid valve. The amount of exhaust gas admitted into the engine is then controlled by a vacuum operated EGR valve under all operating conditions.
A thermal vacuum valve (TVV), thermal vacuum switch (TVS) or an electrically operated solenoid controls operating vacuum, depending on engine operating temperature, to maintain good cold driveability.
There are 3 types of EGR systems used, the vacuum modulated (ported vacuum), the exhaust back-pressure modulated, and the pulse width modulated systems. The major difference between the EGR systems is the method used to control how far each valve opens.
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.