I’ve been struggling to dig out the cause of the 171 and 174 codes... but I just recently had a smoke test done and it looks like the throttle bottle is leaking somewhere I’m thinking the gasket.. now after that I have a p0451 code EVAP I’ve deleted it I don’t know if it will come back but Monday Ill have the throttle body gasket replaced and inspected for any other leaks. I’ve never had any of these codes before except a cylinder 4 misfire and it was stored not actually confirmed. Mercedes says I’ve got compression and it’s an injector and I plan to replace that I’ve done plugs and coils and nothing. My main concern is this new p0451 EVAP code. My gas meter works fine I don’t know what could possibly be causing this now.. I’ve got new purge valve, electric change over valve. Mercedes says neither of my air pump check valves are holding vacuum.. would this cause the p0451? Please help .

 

Any updates?