hmillham

Driving 2008 GL320: My Check engine light came on then about 5-10 sec. later the Glow plug light came on, all while the car stated normal. So I attached my ODB reader and it gave me the P0444 code. I thought glow plug issues were in the P0600's series. Anyone have any ideas?

alx

p0444 is pretty much the system telling you it cant maintain proper vacuum in tank.

lowest hanging fruit is check gas cap

other culprits are more involving and require das readout

hmillham

Thanks...I'll check the gas cap now. That might make since I had just filled her up.

Fourdiesel

If you have a gas cap then you are in a world of hurt! Diesel only please!

Not at all sure that a vacuum is required on the GL 320.

hmillham

Hahaha...opened and reclosed the RED diesel thing-a-ma-gigigy and the light'S when out. Its all good now
Thanks for all the help...I love this place!

alx

there is always vacuum as this is how leaks are detected.

no vacuum = leak.

leak = bad

hmillham

Thanks ALX

Fourdiesel

I agree that if vapor leaks are bad then a vacuum switch is a good way to detect the problem
The reason I mentioned it is because there is no emissions reason for controlling diesel vapors as there is for gasoline vapors. Diesel has a much higher vapor pressure and the vapors that do come from diesel are not as harmful to the environment. Thus no emissions reason to alarm at the first sign of a leak. If the leak detection system exists on the diesels it is not for emissions reasons.

alx

Vacuum in diesel tank is monitored for one reason only- detect leaks.