A P0496 code on your 2019 Mercedes-Benz C-Class indicates the ECM has detected high purge flow when purge shouldn't be occurring. This suggests fuel vapors are entering the intake when the system should be sealed.
Understanding the Fault
P0496 differs from other purge codes by indicating flow when none should exist. The purge valve should be closed during certain conditions, but the ECM detects that vapors are still flowing into the intake—suggesting the valve is stuck open or leaking.
C-Class Engine Configuration
The 2019 C-Class offers turbocharged four-cylinder engines in C300 trim and optional C43 AMG variants. All use electronically controlled EVAP purge systems. The purge valve should seal completely when de-energized.
Causes of Unwanted Purge Flow
A purge valve stuck in the open position allows continuous vapor flow. Internal valve wear prevents complete sealing. Carbon or debris prevents the valve from closing fully. Incorrect valve installation (vacuum lines reversed). A failed purge valve solenoid energized continuously due to ECM or wiring issue.
Diagnostic Approach
Use Mercedes XENTRY to verify the fault. With the engine running at idle and purge commanded off, monitor fuel trim—significant enrichment suggests vapor leakage. Disconnect the purge valve vacuum line—if fuel trim changes significantly, vapors were entering through the valve. Test the valve's ability to seal by applying vacuum when de-energized.