Ah_gl450

Hi All—

My GLS currently has 18k miles on it and yesterday got the check engine light. First thing I checked was the gas cap, and surely it was loose and barely on. So tightened it and closed it. However the light has not gone away.

Ive scheduled an appt with Mercedes but the earliest they have is Friday. Trying to figure out what it is and if I can go on a 400 mile round trip.

Im not sure how long it takes for the CEL to reset after the gas cap has been closed. Also my service B is overdue by 1500 miles, but I don’t think that should be related.

Plutoe

Go to any auto zone and they will read the fault, once known post

wyatt88

Not sure it applies to the GLS, but on a Volvo I owned with a very hard to close gas cap, it would take about 24 hours for the check engine light to extinguish after properly closing the cap.

Boraxo

Same problem, it is not the gas cap as we refilled multiple times and tightened it. Originally lgiht was intermittent but now 24/7.
Naturally this occurred a couple of months after the expiration of our 7/100 extended warranty on our 2017 GLS!

Indy mechanic provided the following report from the code reader:

• The position sensor for the intake cam shaft (cylinder bank 1) has a malfunction
• The position sensor for the intake cam shaft (cylinder bank 1) has a short circuit to ground
• The position sensor for the intake cam shaft (cylinder bank 1) deviates from the specified value. The commanded position cannot be reached.

Can somebody explain what this means in plain english for a guy who knows nothing about engines? Thank you.

John CC

The position sensor for the intake cam shaft (cylinder bank 1) has a malfunction causing it to deviate from the specified value because it is shorted to ground. Find the short to ground of the cam sensor circuit and fix it.