Diagnostic Trouble Code (Dtc) P0442 Evaporative Emission (Evap) Control System Small Leak Detected - Isuzu 1999 RODEO Workshop Manual

6E1–256 RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION
DIAGNOSTIC TROUBLE CODE (DTC) P0442 EVAPORATIVE EMISSION (EVAP)
CONTROL SYSTEM SMALL LEAK DETECTED
Circuit Description
The evaporative system
components:
f Fuel tank.
f EVAP vent solenoid.
f Fuel tank pressure sensor.
f Fuel pipes and hoses.
f Fuel vapor lines.
f Fuel cap.
f EVAP canister.
f Purge lines.
f EVAP canister purge valve.
f EVAP service port.
The evaporative emission system is checked by applying
vacuum to the EVAP system and monitoring for a vacuum
decay. The PCM monitors the vacuum level through the
fuel tank pressure sensor signal. At an appropriate time,
the EVAP canister purge valve and the EVAP vent
solenoid are turned ON, allowing the engine to draw a
small vacuum on the entire evaporative emission system.
After the desired vacuum level has been achieved, the
EVAP canister purge valve is turned OFF, sealing the
system. A leak is detected by monitoring for a decrease in
vacuum level over a given time period, when all other
variables remain constant. A small leak in the system will
cause Diagnostic Trouble Code P0442 to be set. DTC
P0442 is a type A code.
includes the following
Conditions for Setting the DTC
f The BARO is greater the 72.3 kPa.
f No: MAP, TPS, IAT, ECT, EGR, EVAP, VSS, or System
Voltage Diagnostic Trouble Codes.
f IAT and ECT at startup are between 3.5°C(38°F) and
32°C (90°F).
f The difference between IAT and ECT at startup is less
than 6.75°C (12.2°F).
f Vehicle Speed is less than or equal to 98 km/h (60
mph).
f Fuel Level counts vary by less than 8 counts in a 0.125
second time frame.
f The Fuel Tank Level Sensor reads between 10% and
90%.
f Maximum Engine Run time is at least 540 seconds.
f The difference between the actual Fuel Tank Pressure
and the expected Fuel Tank Pressure is less than the
PCM's expectation.
f Fuel Tank Pressure slope is less than or equal to 1mm
(0.03 inches) of water.
The above conditions are met, and the following condition
is met once:
f A single 15 second vacuum decay slope and three 5
second vacuum slopes are all greater than or equal to
the PCM's upper threshold.
Action Taken When the DTC Sets
f The Malfunction Indicator Lamp (MIL) will illuminate.
D06RX056