I have a 2002 Dodge Intrepid, 3.5 ltr engine. The evaporative recycle system uses the new 2nd generation NVLD system. I hadCode P0452 pop up.
I did the key thing...on,off,on,off,on and could read the code on the odometer. A search on this forum told me that Code P0452 indicated a fault in the - Evaporative Emission Control System Pressure Sensor Low Input . (Switch stuck closed)
Didn't make much sense to me so I took it into the local Dodge dealer and had him plug in his specialized scan tool to verify the code.
He told me he has seen quite a few of these codes pop up and the fix was to replace the charcoal canister with attached NVLD switch and this would fix the problem. I priced it at $113 Canadian at the dealer. He also told me the gas tank and the rear sway bar had to be dropped to replace the unit. I ordered the part and booked the repair for a week later. In the meantime, I jacked up the car to take a look at the unit. I found it attached to the rear passenger side of the plastic gas tank with 3 snaps. It was easy enuf to undo the bottom 2 but the top was a challenge. I used a long screwdriver to force the top snap off. At this point, it should have slid down and out but it was too close to the frame so I see why they need to drop the gas tank to give it clearance. However I took a long look and found that if I cut one of the snaps off, (the lower outer snap), it would easily slip out the bottom without the need to remove the gas tank or sway bar. I simply drilled a hole in the remaining bottom snap and secured it with a screw to keep it securely in place. After cutting the bottom snap, and prying the canister away from the other 2 snaps, voila, it lowered enough to get my hand up to the top and disconnect the hose on the side of the NVLD switch which was easily removed with a long screwdriver and some pulling with the other hand. There are two hoses going to the canister, but before I removed the second I had to remove the NVLD switch. It was easily removed by pulling up on the lock tab and rotating it about 30 degrees counter clockwise. You can see the lock tab by searching the web or using a small mirror and light. Then I slowly removed the top hose connected to the canister by rotating it back and forth in a circular fashion while pulling upwards.
At this point the canister can be lowered and removed. Take care not to lose the rubber grommet that fits between the NVLD swith and the canister. Now you can rotate the NVLD switch and remove the 3 wire electrical connector. I am an Instrument Electrical Technician, so I felt justly qualified to take the NVLD switch apart, which is surprisingly easy enough to do and check the internal connections. Since the code P0452 states that the switch is stuck closed, I confirmed this with my ohmeter. I checked all connections, and adjusted the switch open, put it all back together and hoped for the best. Instead of disconnecting the battery to clear the code, simply uplug the two small red 10 amp fuses that go to the PCM in the fuse box beside your window washer fill tube. They are marked inside the fuse box cover. Unplug for 10 minutes and your codes are cleared. BTW this is not necessary as they will clear themselves after 3 complete warm, cool drive cycles, but pulling the fuses makes it a faster fix. Unfortunately, after 3 cycles, the light reapeared. So I went down to the Dodge dealer and bought the new canister with attached NVLD swith. I removed the old one and reinstalled the new one. It has been 2 days now and many cycles and the light has not come on. Problem solved. I saved myself the $120 labor they would have charged to drop the gas tank and install it by doing it myself. Hopefully this will save someone else some money and headaches when Code P0452 pops up.