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.
Diesel (ALH)
Testing the EGR system is done in function 04 (Basic setting). This procedure activates the EGR valve every 10 seconds to make it possible to read the extreme values for EGR (Mass Air Flow Sensor) in display field 3.
- Connect scan tool and select control module for engine electronics with the "address word" 01. Engine must run at idle during this:
- Press buttons "0" and "4" for the function "initiate basic setting" and press "0" button to confirm input.
- Press buttons "0" "0" and "3" for the "Display group number 3" and press "0" to confirm input.
Display field 2 must switch between EGR active and EGR not active every 10 seconds.
Display field 3 and 4 must move in the following control range:
EGR not active
- Specified value in display field 3: 400 to 580 mg/H
- Specified value in display field 4: 0 to 5%
EGR active
- Specified value in display field 3: 150 to 340 mg/H
- Specified value in display field 4: 95 to 100%
If specifications are not obtained, see appropriate diagnostic information.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.