P0456 Evap Very Small Leak - Isuzu 2000 Trooper Workshop Manual

6E–344
TROOPER 6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P0456 EVAP Very Small Leak
Circuit Description
The evaporative system
components:
D Fuel tank
D EVAP canister vent solenoid
D Fuel tank pressure sensor
D Vapor lines
D Fuel cap
D Evaporative emissions canister
D Purge lines
D EVAP canister purge solenoid
The evaporative leak detection diagnostic strategy
is based on applying vacuum to the EVAP
systemand monitoring vacuum decay. The
powertrain control module(PCM)monitors vacuum
level via the fuel tank presuure sensor input .At an
appropriate time, the EVAP canister purge
solenoid and the EVAP canister vent solenoid are
turned "ON," allowing engine vacuum to draw a
very small on the entire evaporative emissions
system. After the desired vacuum level has been
achieved, the EVAP canister purge solenoid is
turned "OFF", sealing the system. A leak is
detected by monitoring for a decrease in vacuum
level over a given time period, all other variables
remaining constant.
A very small leak in the system will cause DTC
P0456 to be set.
includes the following
Conditions for setting the DTC
D No MAP DTC's set.
D No TPS DTC's set.
D No IAT DTC's set.
D No ECT DTC's set.
D No tank pressure sensor DTC's set.
D Baro is more than 70KPa.
D A vacuum decay condition, indicating a very small leak,
is detected during the diagnostic test.
Action Taken When the DTC Sets
D The PCM will illuminate the malfunction indicator lamp
(MIL) after the second consecutive trip in which the
fault is detected.
D The PCM will store condition which were present when
the DTC was set as Freeze Frame and in the Failure
Records data.
Warm up cycles have occurred without a fault.
Conditions for Clearing the MIL/DTC
D The PCM will turn the MIL "OFF" on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condition is no longer present.
D A history DTC P0456 will clear after 40 cosecutive trip
cycle during which the warm up cycles have occurred
without a fault.
D DTC P0456 can be cleared using the Tech 2 "Clear
Info" function or by disconnecting the PCM battery
feed.
D06RY00128