Hello MB enthusiast,

I started getting a check engine light on my 2017 GLS 450, and my diagnostic scan is reporting the following:

Code: P1523-00
Description: The check valve of the evaporative emission control system (at partial load) is jammed open.

I’ve seen a thread suggesting this can be related to engine oil level. I’ve checked the oil level with the dipstick and it’s within spec, and the oil was changed recently.

At the moment the vehicle is driving normally with nothing noticeably wrong.

I’d appreciate any tips, insight, or experience others have had with this code on the M276 engine.

Thanks in advance for your help!

 

First easy check is the vacuum check valve.

Theres a bunch of valves all over the system including Evap solenoid. Can smoke test…

What scanner are you using and can you dig deeper?

 

I’m using a ThinkCar Mini scanner. I realize it’s not Mercedes-specific, so the description may not be fully accurate. From what I’ve been reading, this code could be related to one of the camshaft adjuster magnets/solenoids (VVT). Thanks for chiming in!

 

unless the code reader is very wrong, this has nothing to do with oil or vvt. This is related to either crankcase pressure, gas tank pressure, or the secondary air injection system.

you need to narrow it down. The cheapest scanner that people like is launch creader. I use xentry. If you believe it is electrical, you need to figure out how to use the computer to activate the circuits/valves to check them. If it is a manual pressure activated check valve, then you would rely on smoke testing the system by pulling off different hoses and trying to send the smoke in the wrong direction so to speak… or use mouth, but that doesn’t fit everywhere