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Help diagnosing CEL Error Codes P1701 & P1704 - Vacuum leak?
Hi Everyone,
My car is a 2005 CLK 500 Coupe (W209) and my Check Engine Light is on. I did a scan and got codes P1701 and P1704 (System too lean in banks 1 and 2). Can you guys please help me diagnose this? From what I read, I will need to do a smoke test to determine the source of the leak.
Question, can someone point out in the picture where I'll be blowing smoke to test for the leak?
Also, I recently had my engine gaskets replaced - not by MB professional, but a somewhat-trusted mechanic who has been working on Mercedes his whole life. By the looks of it, it wasn't a super clean job, so I'm suspecting there may be a leak in the gasket.. Is that possible?
Looks like your mechanic used red RTV to seal the breather covers. The colors of these sealants are usually indicative of there adhesive and temperature handling properties. In this case, red RTV is the wrong sealant, so it's possible the leak is there. The highest temp black RTV you can get is acceptable, but really, I'd use a sealant with the proper specs, like these:
As for finding the leak, check all around those breather covers, as well as around all the rubber vacuum hoses on the engine, coming back to the throttle.
Looks like your mechanic used red RTV to seal the breather covers. The colors of these sealants are usually indicative of there adhesive and temperature handling properties. In this case, red RTV is the wrong sealant, so it's possible the leak is there. The highest temp black RTV you can get is acceptable, but really, I'd use a sealant with the proper specs, like these:
As for finding the leak, check all around those breather covers, as well as around all the rubber vacuum hoses on the engine, coming back to the throttle.
Rudeney, thank you for the helpful info. Do you know exactly which hoses I'll be blowing smoke in to test for a leak? Any of the entry points below?
There are hoses on both breathers. There are vacuum hoses on the front of the engine for the secondary air pump. There is a vacuum hose on the back of the throttle body for the EGR valve and the brake boost. Check all of those.
02-20-2016, 02:44 PM
