System Description
A restricted or blocked evaporative emission (EVAP) vent path is detected by the control module commanding the purge valve ON (open) and the vent valve ON (closed) allowing a vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the control module commands the purge valve OFF (closed) and the vent valve OFF (open) while monitoring the fuel tank pressure (FTP) sensor for a decrease in vacuum. If the vacuum does not decrease to near 0 inches H2O in a calibrated time, this DTC sets.
DTC Descriptors
This diagnostic procedure supports the following DTC:
DTC P2422 Evaporative Emissions (EVAP) Vent System Performance
Conditions for Running the DTC
| • | The engine is running. |
| • | DTC P2422 runs continuously once the above condition is met. |
The engine is running.
Conditions for Setting the DTC
| • | Fuel tank pressure is less than -3 kPa (-12.5 inch H2O) at cold engine startup. |
| • | The above condition is present for at least 13 seconds. |
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
An intermittent condition could be caused by a damaged EVAP vent housing, a temporary blockage at the EVAP vent valve inlet or a pinched vent hose. A blockage in the vent system will also cause a poor fuel fill problem.
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Values | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
Schematic Reference: Evaporative Emissions Hose Routing Diagram | ||||||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | |||||
2 | Did DTC P0444, P0445, P0447, P0448, P0451, P0452, P0453, or P0454 set? | -- | Go to Step 3 | |||||
3 |
Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 4 | ||||
Does the scan tool indicate fuel tank pressure near the specified value? | 0 in H2O | Go to Step 5 | Go to Step 8 | |||||
5 |
Is the FTP sensor within the specified range? | -1 to +1 in H2O | Go to Diagnostic Aids | Go to Step 6 | ||||
6 | Disconnect the EVAP vent hose from the EVAP vent valve. Does the scan tool indicate fuel tank pressure near the specified value? | 0 in H2O | Go to Step 10 | Go to Step 7 | ||||
7 | Disconnect the EVAP vent hose from the EVAP canister. Does the scan tool indicate fuel tank pressure near the specified value? | 0 in H2O | Go to Step 13 | Go to Step 11 | ||||
8 | With a scan tool, observe the fuel tank pressure sensor voltage. Is the FTP sensor voltage more than the specified value? | 4.3 V | Go to DTC P0453 | Go to Step 9 | ||||
9 | Test for poor connections at the harness of the fuel tank pressure sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 12 | ||||
10 | Replace the EVAP vent valve. Did you complete the replacement? | -- | Go to Step 14 | -- | ||||
11 | Replace the EVAP canister. Did you complete the replacement? | -- | Go to Step 14 | -- | ||||
12 | Replace the fuel tank pressure (FTP) sensor. Did you complete the replacement? | -- | Go to Step 14 | -- | ||||
13 | Repair for a blockage in the EVAP vent hose. Did you complete the repair? | -- | Go to Step 14 | -- | ||||
14 |
Is the FTP sensor within the specified range? | -1 to +1 in H2O | Go to Step 15 | Go to Step 3 | ||||
15 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||
