Hello all, I'm trying to take care of an issue causing a CEL to come on, it is code P0452. My computer says "Tank pressure sensor, short circuit to ground". Does anyone have any advice on where I should start? I'm happy to just replace the tank pressure sensor, but I have no idea where it is. It is a 2006 ML-350. Thanks for reading! -Monte

Monte, what module was this code stored in?

Do you have a scanner or just a code reader?

The first thing you should do is remove the right rear wheel well lining and see if the pressure sensor is located there.

Remove the tire and then remove the wheel well lining.

I have a scanner with a computer interface. I can even make keys.

Did you look at post #3?

Thanks Maj, yes I did. It has been pouring rain and my shop is too full of machining equipment for me to be able to fit a vehicle in at present so I'm waiting until the weekend when the rain is supposed to stop to look for the sensor. Once I find the sensor what is the next step in diagnosis?

Also, not related to this thread, but when the gears for my door lock grind (pop pop pop pop pop pop pop pop) is it the brass worm screw that usually fails, or the gear that drives the brass worm screw? I may have to replace the actuator because now I'm getting the message "door lock actuator closed circuit to ground". I don't want to tear apart the door panel until I have all the parts to fix it, right now all I have is the brass worm screws..

Hey, just want to say thanks for all your help. If you ever need any parts milled don't hesitate to ask.

-Monte

Amazon has the repair kit for all springs.

Thanks man, I'm going to order it now! Still a little worried about the new error message "passenger door lock actuator closed circuit to ground"...the passenger door lock has always had issues, but it was only recently that we started seeing this fault code. But it's still making noise, so the actuator is obviously working.

-Monte

Monte, whenever there is a new problem you must open thread on that issue and please include the code #.

My diagnostic computer does not show a "code" per se, it will show OBD codes, but most of the time I don't get any when I do an OBD code scan. For the more in depth scan that reads each computer it just gives me a description of the issue which doesn't appear with an OBD scan. That's the description it gave me. "Passenger door lock actuator closed circuit to ground". No code.

Good afternoon Maj. I finally got around to looking for the fuel pressure sensor. I took off the right rear wheel and peeled back the wheel lining. Everything looks as described in the picture but the tank pressure sensor I ordered looks nothing like the one mounted to the box you circled in your picture. That one has two leads, the one I got has 3. This is a pic of the one I got. Is there another tank pressure sensor somewhere? Some people say there is one under the rear seat.

Also, say the picture you sent IS the tank pressure sensor, how does it come out? Looks like there is a plastic "cap" at the top of the sensor...do I open the top of the box you circled and remove a retaining clip or something? Or does that cap on top of the sensor unscrew? I don't want to break it...

Thanks again!

You have to remove the fuel tank.

Just printed out all 3 docs you provided links for and studying them. I really don't want to remove the fuel tank unless it's absolutely necessary. I have not smelled any gas smells so I don't think there is a leak. Am I understanding that there are indeed 2 pressure sensors in the EVAP system? One like you showed in post number 3 and another on top of the fuel tank? If so I would like to test the sensor you showed in pump 3 before dropping the tank. I already have it exposed, do you know how that thing comes out? Fortunately the truck drives fine, great gas mileage (well, great for an ML350), easy starts, so I should be able to just drive it around till it's out of gas so I can drop the tank with relative ease. Most of the time I have to drop a fuel tank it's full of gas and vehicle isn't running so this time around it should be a little easier! But yea, should I do anything with that sensor you showed in post #3 first? And any other checks I can do first before dropping the tank that you know of I would definitely appreciate knowing about.

Thanks,
Monte

the item in the photo of the rear wheel area is a vent valve. There are not two fuel tank pressure sensors.