I recently took my 07 Grand caravan to the shop with the po452 code. he replaced the pressure sensor switch. and wife drove it around and after about 50 miles the check engine light came back on .. with the same code .. what gives.. what could be possibles problems??? i already replace the gas cap..

 

Welcome to DF
If you like I have the PDF file for code P0452. I can send it to you by email. This the shop can fix the problem. Here is part of the File.
Symptom:
P0452-NVLD PRESSURE SWITCH SENSE CIRCUIT LOW
When Monitored and Set Condition:
P0452-NVLD PRESSURE SWITCH SENSE CIRCUIT LOW
When Monitored: Immediately after engine start up.
Set Condition: The PCM activates the NLVD Solenoid. If PCM does not see NVLD switch
open, an error is detected. One Trip Fault.
POSSIBLE CAUSES
GOOD TRIP EQUAL TO ZERO
VEHICLE HISTORY AND SERVICE BULLETIN INVESTIGATION
EVAP PURGE SOLENOID LEAKS/STUCK OPEN
NVLD SWITCH OPERATION
NVLD ASSEMBLY
(K107) NVLD SWITCH SIGNAL CIRCUIT SHORTED TO GROUND
PCM
TEST ACTION APPLICABILITY
1 Start by reading PCM DTC(s) and record the related Freeze Frame data in any
DTC(s) are present.
Check the vehicle repair history.
If the vehicle has a repair history that pertains to the customer’s current complaint,
review the repair.
Inspect the vehicle for any aftermarket accessories that may have been installed
incorrectly.
Check for any service bulletin(s) related to the customer’s complaint or DTC(s).
If a service bulletin applies, follow the instructions per service bulletin.
Did the service bulletin repair the customer’s complaint?
All
Yes ! Testing Complete.
Perform POWERTRAIN VERIFICATION TEST VER - 6.
No ! Go To 2
2 Check for any related TSBs before continuing.
Ignition on, engine not running.
With the DRBIIIt, read DTCs and record the related Freeze Frame data.
Is the Good Trip Counter displayed and equal to zero?