The P0618 code in your 2023 Mercedes-Benz GLC indicates a communication error between the engine control module and an alternative fuel control module via the CAN (Controller Area Network) bus. This code typically appears in vehicles equipped with alternative fuel systems like natural gas or hydrogen fuel cells. However, in your standard GLC, this code may indicate a misdiagnosis or a software-related issue.
When This Code Appears in Standard Vehicles
The 2023 GLC in standard gasoline or diesel configuration shouldn't have an alternative fuel control module. P0618 appearing in your vehicle likely indicates ECM software confusion, an incorrect vehicle configuration in the module, or a misread code. Hybrid versions of the GLC do have additional powertrain modules that may be involved.
CAN Bus Communication Basics
All modules in your GLC communicate through the CAN bus network. When one module can't communicate with an expected module, communication error codes result. If the ECM is programmed to expect an alternative fuel module that doesn't exist, it will report communication failures.
Possible Causes
Incorrect ECM programming for your vehicle's configuration is the most likely cause. A recent software update may have introduced a bug. In rare cases, aftermarket modules or devices connected to the OBD-II port cause phantom communications. If you have a plug-in hybrid GLC, the high-voltage battery control module communication should be checked.
Diagnostic and Resolution
Using Mercedes-Benz XENTRY or Star Diagnostic, verify the ECM's vehicle configuration matches your actual build. Check for software updates that address this issue. If the configuration is incorrect, the ECM needs reprogramming with the correct calibration. Your 2023 GLC is fully covered under warranty for any software or control module issues.