Was the code perchance a P0451? Not a P0541? A P0451 code refers to an issue with the fuel tank pressure sensor. A P0541 is a pre-heater code for a Cummins diesel and isn't applicable to your car as it lacks the parts and ability to set that code.
A P0451 code is set if the VPS detects a large change over a short period of time. Now because of that code and it's criteria I would actually start by testing the purge valve. If it was stuck open or failed while the car was at an idle the vacuum in the tank would change unexpectedly because the ECM didn't command it to purge. So I would verify that before going to test the sensor. It looks like the image below and is in the lines below the air inlet to the throttle body. Testing is simple, disconnect the valves electrical connector, remove the lines and the valve and try to blow through it. With no power it should be closed, so if you can blow through it, it's defective. If you cannot, reinstall it and we will look at the pressure sensor. If you have access to an OE level scan tool this is easy, you would simply watch the tank vacuum levels and compare them to the sensors output as you control the valve for vacuum. Without that you have a couple options, use a multimeter to measure the voltages and grounds to the sensor, or just replace the sensor and see if the code goes away. The sensor is underneath the car next to the charcoal canister Testing without a scan tool is sort of simple, take a voltmeter and test for voltage between the Yellow and Brown wires in the connector with the key on. There should be 4.5 to 5.5 volts. If you have that then change the sensor and see if the code goes away. There isn't really any other testing if the power is there because you cannot see the real time data without a scan tool.
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Mar 29, 2026 at 10:40 AM
