Experiencing communication issues with your Mercedes-Benz W211, specifically encountering the dreaded “Data Transfer Has Failed Das To Xentry” error during diagnostics? This problem can be incredibly frustrating, hindering your ability to accurately diagnose and repair your vehicle. As an automotive repair expert at xentryportal.store, I understand the complexities of modern vehicle electronics and communication networks. This article delves into a real-world case of CAN bus problems in a W211 chassis Mercedes-Benz, offering insights into diagnosing and resolving communication failures that often trigger the “data transfer has failed DAS to Xentry” message.
The owner of a W211 model experienced intermittent and perplexing issues. Initially, the car exhibited a range of electrical malfunctions while being driven – warning lights illuminated, ABS/ESP systems reported errors, interior lights flickered erratically, and the air conditioning fluctuated between hot and cold. Adding to the concern, a ‘red battery’ symbol appeared, suggesting alternator problems. A diagnostic scan using Xentry, the professional diagnostic tool for Mercedes-Benz, revealed a startling number of stored fault codes. Nearly every module reported communication failures, indicating widespread issues across both the powertrain and body CAN bus systems. The diagnostic report, spanning eight pages, detailed numerous instances of modules unable to communicate with each other, alongside messages suggesting CAN bus shorts and shutdowns. Crucially, most faults were intermittent (indicated by lowercase ‘f’ in Xentry), meaning they had occurred but were not currently active.
Initial investigation focused on the physical CAN bus network. A thorough inspection of CAN bus distributors and wiring harnesses was conducted to identify any signs of corrosion or loose connections. Under the right side of the dashboard, a chafed CAN wire was discovered where the wiring bundle rested against a protective aluminum foot plate. This potential short circuit was addressed by repairing the wire and rerouting the harness to prevent future abrasion. While this addressed a potential wiring fault, the underlying issue persisted.
Adding another layer of complexity, the vehicle had undergone prior oil cooler seal replacement at an independent shop. Unfortunately, intake manifold gaskets and o-rings were not correctly replaced during this service, leading to soot accumulation throughout the engine bay, heavily coating the alternator. Suspecting a failing alternator due to contamination, it was preemptively replaced along with proper intake gasket repairs and thorough cleaning. Despite these efforts, the car initially seemed repaired, running well for about a month.
However, the gremlins returned. This time, the car failed to start completely. Upon attempting to start, there was no engine cranking at all. Another diagnostic session with Xentry yielded a similar, though not identical, set of CAN bus communication fault codes. Interestingly, the car started without issue once it was back at the owner’s residence. The tow truck driver confirmed the no-start condition and also noted the inability to shift the car out of Park, requiring the emergency release – further symptoms pointing towards electronic or communication malfunctions.
Seeking expert advice, the owner consulted a service advisor at a Mercedes-Benz dealership. The advisor, a former technician, suggested investigating potential water intrusion, highlighting the rear SAM (Signal Acquisition Module) in the trunk and the ZGW (Central Gateway) under the dashboard as common problem areas in W211 models. Trunk leaks, often due to faulty trunk gaskets, and sunroof drain blockages leading to water ingress down the A-pillar and into the dashboard wiring, were identified as typical causes. The ZGW, positioned under the driver’s side knee cover, is particularly vulnerable as water can wick down the wiring harness directly into its connectors.
Following this advice, the rear SAM area in the trunk was inspected first. A thorough check revealed absolutely no signs of moisture or water damage. The connectors for the body CAN wires at the rear SAM were also found to be in pristine condition. Next, attention shifted to the ZGW module. Upon removing the driver’s side knee cover, the ZGW was located. Disconnecting the ZGW connectors immediately revealed signs of corrosion. Further investigation by removing and opening the ZGW module confirmed internal corrosion, particularly affecting pins 7, 8, 9, and 10 on the connector. These pins correspond to the engine CAN (pins 7 and 8) and body CAN (pins 9 and 10) networks. The corrosion, appearing as green residue, was clearly disrupting electrical conductivity and CAN bus communication.
To rectify the problem, the corroded ZGW module and connector pins were meticulously cleaned using isopropyl alcohol (91%), wooden toothpicks, and cotton swabs. The area was thoroughly flushed with alcohol to remove all traces of corrosion and allowed to dry overnight. After reassembling and reinstalling the ZGW module, the Mercedes-Benz W211 started immediately. Subsequent test drives involving multiple start-stop cycles confirmed the repair’s success.
This case highlights the importance of considering water intrusion and connector corrosion when troubleshooting CAN bus communication issues and “data transfer has failed DAS to Xentry” errors in Mercedes-Benz W211 vehicles. While diagnostic tools like Xentry are essential for identifying communication faults, physical inspection of modules like the ZGW and their connectors is crucial for pinpointing the root cause, especially in vehicles prone to water leaks. If you are facing similar “data transfer has failed DAS to Xentry” messages and communication problems in your W211, inspecting the ZGW module for corrosion should be a priority in your diagnostic process. Addressing this often-overlooked issue can resolve a wide range of seemingly unrelated electrical malfunctions and restore reliable communication throughout your vehicle’s electronic systems.
