EGR (Exhaust Gas Recirculation)

EGR stands for Exhaust Gas Recirculation. It routes a portion of exhaust gas back into the engine intake, which lowers combustion temperatures and reduces nitrogen oxide emissions.

The EGR valve controls how much gas recirculates. The EGR cooler cools that gas before it re enters the engine. Both are common failure points. A clogged EGR valve causes rough running and fault codes. A leaking EGR cooler causes slow coolant loss with no visible drip.

Removing or disabling EGR on a road vehicle is illegal in Canada and the United States.

Mike Turner

Red Seal certified heavy duty mechanic with 14 years turning wrenches on Cummins, Powerstroke and Duramax engines across Alberta and Ontario. Mike writes the guides he wishes existed when he was apprenticing.