Diagnostic Aids

WARNING: This page is about a different car, the 2007 Isuzu i-370, 2007 GMC Canyon, and 2007 Chevrolet Colorado. However, it is still accessible from the selected car via links, so may be relevant.

This diagnostic is designed to detect an unexpected abrupt voltage signal change from the FTP.
Scan tool output controls, snapshot, and plot functions can help detect erratic sensor response. To look at the sensor signal under vacuum conditions, use snapshot and the purge/seal function to capture data while commanding purge to 30 percent, and then plot the data to look for erratic sensor operation. A similar inspection can be done for the pressure side of the sensor range by applying pressure with the J 41413-200 Evaporative Emissions System Tester (EEST) while taking a snapshot.
Ensure that the reference port on the FTP sensor is unobstructed.

DTC P0454

Step	Action	Values	Yes	No
1	Did you perform the Diagnostic System Check - Vehicle?	-	Go to Step 2	Go to Diagnostic System Check - Vehicle
2	Are DTCs P0452, P0453 or P0651 also set?	-	Go to Diagnostic Trouble Code (DTC) List - Vehicle	Go to Step 3
3	Inspect the sensor signal under vacuum using the following procedure: With a scan tool, command the evaporative emission (EVAP) canister vent solenoid valve closed. Command the purge solenoid to 30 percent. Observe the fuel tank pressure (FTP) sensor voltage parameter as the vacuum increased to the abort limit. Did you observe an erratic voltage signal?	-	Go to Step 4	Go to Step 5
4	Inspect for an intermittent a for a poor connection at the FTP sensor. Refer to Testing for Intermittent Conditions and Poor Connections . Did you find and correct the condition?	-	Go to Step 7	Go to Step 6
5	IMPORTANT: Do not exceed the specified value. Exceeding the specified value may produce incorrect test results. Inspect the sensor signal under pressure using the following procedure: Connect the J 41413-200 Evaporative Emissions System Tester (EEST) to the fuel fill pipe. Turn ON the ignition, with the engine OFF. With a scan tool, command the EVAP canister vent solenoid valve closed. Turn the nitrogen/smoke valve on the J 41413-200 control panel to NITROGEN. Use the remote switch to pressurize the EVAP system to the specified value. With a scan tool, observe the FTP sensor in volts. With a scan tool, command the EVAP canister vent solenoid valve open. Did you observe an erratic voltage signal?	5 in H2O	Go to Step 4	Go to Diagnostic Aids
6	Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement . Did you complete the replacement?	-	Go to Step 7	-
7	Turn OFF the ignition. Remove the fuel filler cap. Turn ON the ignition, with the engine OFF. Is the FTP sensor parameter within the specified value?	-1 to +1 in H2O	Go to Step 8	Go to Diagnostic Aids
8	With a scan tool, observe the Capture Info. Are there any DTCs that have not been diagnosed?	-	Go to Diagnostic Trouble Code (DTC) List - Vehicle	System OK