So I have been running into the perpetual P0410 code on my ML320 for the last year or so and continue to look for a solution.

• I have cleaned the manifold/hoses from top to bottom
• Eliminated possible vacuum leaks with smoke test
• Replaced the EGR
• Replaced the Secondary Air Pump.
• Cleaned the Air-Injection Check Valves and ports
• Replaced the Air Injection Control Valve
• Replaced the gasket around the intake pipe at the manifold opening and MAF.

I am starting to believe the issue is with our M112 and M113 Air-Injection Check Valves. Has anybody found a replacement or upgrade for these? It seems like these were poorly engineered and collect a lot of soot at the reeds, inside the openings and the check valve bell. It would be nice to find an upgrade to completely replace these.

TIA
Eric