Conditions for Setting the DTC
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P0451
This DTC will set if the controller is unable to re-zero the FTP sensor voltage within a calibrated range during the engine-off small leak test, P0442.
P0452
The FTP sensor voltage is less than 0.15 V for more than 10 s.
P0453
The FTP sensor voltage is more than 4.9 V for more than 10 s.
P0454
If, during the engine-off natural vacuum small leak test, P0442, the ECM detects an abrupt FTP signal change, other than a refueling event, this DTC will set. An abrupt change is defined as a change of 0.45 in H2O in the span of 1 second but less than 1 in H2O in 12.5 ms.