The On-Board Diagnostics II (OBD2) port in your 2017 Mercedes-Benz E300 is a crucial tool for vehicle maintenance and diagnostics. It’s the gateway for mechanics and car owners to access valuable information about the car’s health, from reading trouble codes to ensuring your vehicle passes emissions tests. So, what happens when this essential port suddenly stops working? You might find yourself unable to perform a smog check or diagnose a check engine light. Before you assume a major electrical problem, there’s a simple fix you should investigate first: a blown fuse.
Often overlooked, a fuse dedicated to the diagnostic port can be the culprit behind a non-functional OBD2 port. In the case of a 2017 E300, locating and checking this fuse can save you time and potentially expensive diagnostic fees. One owner of a 2017 E300 experienced this exact issue and discovered a straightforward solution. After facing a non-responsive OBD2 port, preventing them from getting a smog check, they embarked on a troubleshooting journey that led to a surprisingly simple answer.
The key lies in identifying the correct fuse. For the 2017 E300 model, the fuse you’re looking for is labeled “Diagnostic Port” and is located in the engine bay fuse box. Specifically, it’s fuse number 62, a 15 AMP fuse. Finding the fuse box itself is usually straightforward, but locating the fuse assignment diagram can be less obvious. Many Mercedes-Benz vehicles, including the 2017 E300, cleverly conceal the fuse diagram within the driver’s side dashboard fuse panel. By carefully removing the end cap of this panel, you’ll typically find a folded diagram detailing the fuse layout.
Once you have the diagram, carefully examine the list of fuses. Initially, you might search for terms like “ECU Port” or “OBD Port,” but in the 2017 E300, the fuse is specifically labeled “Diagnostic Port.” Cross-reference this with the fuse location diagram to pinpoint fuse number 62 and its 15 AMP rating.
In the aforementioned owner’s experience, the mystery deepened when they discovered the fuse bay for the diagnostic port was empty. This raised questions, especially considering the vehicle was purchased from a Mercedes-Benz dealer and regularly serviced there. While the exact reason for the missing fuse remained unclear, a likely scenario emerged involving a recent alternator replacement at a local repair shop. It’s plausible that during this service, the fuse was inadvertently removed and not replaced.
Regardless of how it happened, the solution was simple: installing a new 15 AMP fuse in bay number 62 restored power to the diagnostic port, bringing it back to life. This allowed the owner to proceed with their smog check and address any pending fault codes.
If you’re experiencing a non-functional OBD2 port in your 2017 E300, checking the “Diagnostic Port” fuse should be your first step. It’s a quick, easy, and free check that can resolve the issue and save you from unnecessary complications. Consult your vehicle’s fuse diagram and owner’s manual for precise locations and fuse specifications. While a missing or blown fuse is a common and simple fix, always consult a qualified mechanic if you encounter persistent issues or are uncomfortable performing these checks yourself.
