EGR

📖 YOUCANIC Automotive Glossary

The EGR (Exhaust Gas Recirculation) system routes exhaust gas into the intake manifold to lower combustion temperatures and reduce NOx emissions. By diluting the mixture with inert exhaust gas, peak combustion temperature drops by hundreds of degrees. Modern EGR valves use electronic motors with position feedback. The valve stays closed at idle and WOT, opening during light-moderate cruising.

EGR valves are prone to carbon buildup causing sticking. Stuck-open: rough idle, stalling, loss of power. Stuck-closed: engine knock, increased NOx. DTCs: P0401 (Insufficient Flow), P0402 (Excessive Flow). DIYers can often clean carbon-fouled valves rather than replacing. After cleaning or replacement, perform an EGR Reset with your scanner to clear learned position values.