Having problems with your Chevrolet Silverado 1500 ?

Po455 code coming up on my scanner - Silverado 1500 Chevrolet Cars & Trucks

Posted / edited by AnonymousUser on : 16-01-2017

Answers :

Hi there:DTC P0455 - Evaporative Emission (EVAP) System Large Leak Detected

The control module tests the evaporative emission (EVAP) system for a large leak. The control module monitors the fuel tank pressure (FTP) sensor signal to determine the EVAP system vacuum level. When the conditions for running are met, the control module commands the EVAP canister purge solenoid valve open and the EVAP canister vent solenoid valve closed. This allows engine vacuum to enter the EVAP system. At a calibrated time, or vacuum level, the control module commands the EVAP canister purge solenoid valve closed, sealing the system, and monitors the FTP sensor input in order to determine the EVAP system vacuum level. If the system is unable to achieve the calibrated vacuum level, or the vacuum level decreases too rapidly, this DTC sets.
The table illustrates the relationship between the ON and OFF states, and the Open or Closed states of the EVAP canister purge and vent solenoid valves.

This diagnostic procedure supports the following DTC:

CONDITIONS FOR RUNNING THE DTCBefore the powertrain control module (PCM) can report DTC P0455 failed, DTC P0496 must run and pass.DTCs P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0131, P0132, P0133, P0134, P0135, P0136, P0137, P0138, P0140, P0141, P0151, P0152, P0153, P0154, P0155, P0156, P0157, P0158, P0160, P0161, P0220, P0442, P0443, P0449, P0451, P0452, P0453, P0454, P0464, P0496, P0502, P0503, P1111, P1112, P1114, P1115, P1121, P1122, P1125, P2135 are not set.The engine is running.The ignition voltage is between 10-18 volts .The barometric pressure (BARO) is more than 75 kPa .The fuel level is between 15-85 percent .The engine coolant temperature (ECT) is between 4-65 degrees C (39-149 degrees F) .The intake air temperature (IAT) is between 4-75 degrees C (39-167 degrees F) .The start-up ECT and IAT are within 9 degrees C (16 degrees F) of each other.DTC P0455 runs once per cold start.

CONDITIONS FOR SETTING THE DTC The EVAP system is not able to achieve or maintain vacuum during the diagnostic test.

ACTION TAKEN WHEN THE DTC SETSThe 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/DTCThe 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 AIDSTo help locate intermittent leaks, use the J 41413-200 Evaporative Emission System Tester (EEST) to introduce smoke into the EVAP system. Move all EVAP components while observing smoke with the J 41413-SPT High Intensity White Light. Introducing smoke in 15-second intervals will allow less pressure into the EVAP system. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.
A temporary blockage in the EVAP canister purge solenoid valve, purge pipe, or EVAP canister could cause an intermittent condition. Inspect and repair any restriction in the EVAP system.
To improve the visibility of the smoke exiting the EVAP system, observe the suspected leak area from different angles with the J 41413-SPT.Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.For intermittent conditions, refer to Testing for Intermittent Conditions and Poor Connections. See: Diagrams\\Diagnostic Aids

TEST DESCRIPTIONNumbers below refer to the step numbers on the diagnostic table.
Introducing smoke in 15-second intervals may allow smaller leak areas to be more noticeable. When the system is less pressurized, the smoke will sometimes escape in a more condensed manner.This step verifies proper operation of the FTP sensor.A normal operating FTP sensor should increase above 5 inches of H2O and stop between 6-7 inches of H2O.
Fig: 01Fig. 02Fig. 03

Hope this helps.
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