Q&A

Low turbocharger boost pressure and low engine performance can be caused by leaks in the charge air cooler or it's plumbing. The below procedure outlines how to check for leaks in the charge air cooler system.
· Turbo Resonator: Inspect the resonator (muffler, connected to the turbocharger) for air leaks at the seam between the two shells.
· Exhaust Gas Recirculation (EGR) valve: A sticking EGR valve influences the mass air flow causing implausibility with MAF, which displays one or more DTC's. Don't replace the EGR valve if no DTC's are present. Use the below EGR valve Diagnostic Procedure to determine if replacement is required.
· Mass Air Flow Sensor (MAF): The mass air flow, measured and provided by the MAF is critical for calculations performed by the ECM and may result in several DTC’s related to the air intake system if not accurate.
· Boost Pressure Sensor: Make sure that the correct part with number 5117545AA (Mercedes Benz part number printed on sensor: A 004 153 84 28) or superseding part number is installed. The Boost Pressure Sensor for an OM612 engine would fit mechanically on an OM647 engine but will result in poor performance.
· Turbocharger: Consider that an operating turbocharger creates a flow sound, which is normal and does not require replacement. Other sounds like whistling are potentially caused by the resonator or improper line connections.