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.
Exhaust Gas Recirculation (EGR) system: Function
Vehicles with engine code ALH
Activation of Exhaust Gas Recirculation (EGR) system occurs from Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) -J248- via EGR Vacuum Regulator Solenoid Valve -N18- to EGR valve. The mechanical EGR valve with cone-shaped valve plunger makes different opening diameters possible at different valve lift. Every relevant valve position is possible via cyclic activation.
Removing and installing components of EGR system. Refer to Exhaust Gas Recirculation (EGR) components (vehicles with engine code ALH), removing and installing .
Connection diagram for vacuum hoses. Refer to Connection diagram for vacuum hoses (vehicles with engine code ALH) .
Vehicles with engine code BEW
Activation of EGR system occurs from Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) -J248- via EGR Vacuum Regulator Solenoid Valve -N18- with Potentiometer for EGR -G212-.
Removing and installing components of EGR system. Refer to Exhaust Gas Recirculation (EGR) components (vehicles with engine code BEW), removing and installing .
Connection diagram for vacuum hoses. Refer to Connection diagram for vacuum hoses (vehicles with engine code ALH) .
- Always replace self-locking nuts.
- Engine Control Module (ECM) is equipped with On Board Diagnostic (OBD).
- Components marked with * are tested via On Board Diagnostic (OBD). Refer to Diagnostic mode 3: Check DTC Memory .
NO RELATED
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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.