DTC P0442 Evaporative Emission (EVAP)
System Small Leak Detected
The PCM tests the EVAP
system for the following conditions:
- Large and small leaks
- Excess vacuum
- Purge flow during non-commanded
conditions
- Fuel Level and Fuel Pressure sensor
faults
- EVAP Purge and Vent Valve faults
The PCM monitors the
Fuel Tank Pressure sensor in order to determine the level of vacuum/pressure in
the EVAP system. The PCM commands both the EVAP Purge Solenoid and the EVAP
Vent Valve ON when the Conditions for Running the DTC are met in order to apply
an engine vacuum to the EVAP system. The PCM commands the EVAP Purge Solenoid
OFF once the system has reached a predetermined level of vacuum. The EVAP
system should HOLD the vacuum in the sealed system. The PCM sets this DTC in
order to indicate a small leak if the EVAP system fails to hold a predetermined
level of vacuum for a predetermined length of time. This DTC sets after failing
the above test twice.
Conditions for Running the DTC
- DTCs P0107, P0108, P0112, P0113,
P0117, P0118, P0121, P0122, P0123, P0420, P0430, P0500, P0502, P0503,
P1111, P1112, P1114, P1115 and HO2
- The barometric pressure is greater
than 75 kPa.
- The fuel level is between 15% and
85% of full capacity.
- The engine coolant temperature is
between 4°C (39°F) and 30°C (86°F).
- The intake air temperature is
between 4°C (39°F) and 30°C (86°F).
- The start up engine coolant
temperature and intake air temperature are within 9°C (16°F) of each
other.
Conditions
for Setting the DTC
The vacuum in the EVAP
system decays (leaks) at too fast a rate.
Important
This DTC does NOT report a first
failed test. A first fail of this DTC will have a scan tool status as Not Run.
Use the scan tool data display parameter of EVAP Test Result to determine if
this DTC has failed or passed for this ignition cycle.
Action
Taken When the DTC Sets
- The PCM illuminates the malfunction
indicator lamp (MIL) on the second consecutive ignition cycle that the
diagnostic runs and fails.
- The PCM records the operating
conditions at the time the diagnostic fails. The first time the diagnostic
fails, the PCM stores this information in the Failure Records. If the
diagnostic reports a failure on the second consecutive ignition cycle, the
PCM records the operating conditions at the time of the failure. The PCM
writes the conditions to the Freeze Frame and updates the Failure Records.
Conditions
for Clearing the MIL/DTC
- The PCM turns OFF the malfunction
indicator lamp (MIL) after 3 consecutive ignition cycles that the
diagnostic runs and does not fail.
- A last test failed, or current DTC,
clears when the diagnostic runs and does not fail.
- A history DTC clears after
40 consecutive warm-up cycles, if no failures are reported by this or
any other emission related diagnostic.
- Use a scan tool in order to clear
the MIL and the DTC.
Important
An accurate indication of
fuel level is required for the PCM to properly Pass or
Fail this DTC. Always diagnose fuel level sensor DTC's
before performing this DTC's diagnostic table. Always
inspect for fuel level sensor DTC's stored as
History.
Important
The Service Bay Test may have
to be performed in cold ambient air temperatures when the vehicle is running a
winter grade fuel. The scan tool displays a message when the service bay test
does not run.
Conditions for Running the
- The battery voltage is between 10.5
and 17.5 volts.
- The fuel level is between 15% and
85% of the full capacity.
- The engine temperature is between
3.5°C (38°F) and 35°C (95°F).
The scan tool displays
Test Aborted if any of the above conditions are not met.
Perform a physical
inspection of the EVAP system. Inspect for the following conditions:
- A loose, missing, defective, or
incorrect fuel tank cap
- Incorrectly routed or defective EVAP
system vacuum and vapor lines
- A malfunctioning or damaged vapor
canister
Inspect for charcoal
release from the vapor canister. Refer to the EVAP
System Cleaning procedure.
The vacuum and pressure
in the EVAP system is measured in inches of water (H2O). Most gauges measure
vacuum in inches of mercury (Hg) and pressure in pounds per square inch (psi). The following shows how the values compare:
|
in H2O |
in Hg |
psi |
|
1in H2O |
0.07 in Hg |
0.0361 psi |
|
5 in H2O |
0.36 in Hg |
0.180 psi |
|
10 in H2O |
0.73 in Hg |
0.361 psi |
|
15 in H2O |
1.10 in Hg |
0.541 psi |
The numbers below refer
to the step numbers on the Diagnostic Table.
If the Service Bay Test can not be run, proceed
to step 5. If a fault is not currently present the diagnostic table steps will
return you to step 3.
The Fuel Tank Pressure sensor range is from
7.5 in. H2O of pressure to -17.5 in. H2O of pressure (vacuum).
In order to test the Fuel Tank Pressure
sensor for vacuum response, command the EVAP Purge Solenoid Valve ON with the
engine running and quickly SEAL the system. Leaving the EVAP Purge Solenoid
Valve ON for a longer period of time allows a greater level of vacuum to
develop.
|
Step |
Action |
Value(s) |
Yes |
No |
|
Did
you perform the Powertrain On-Board Diagnostic
(OBD) System Check? |
-- |
|||
|
Are any other EVAP system DTC's
stored in history? |
-- |
Go to applicable DTC |
||
|
Inspect
the EVAP system for the following conditions:
Repair
the EVAP system if needed. Did you find and repair the condition? |
-- |
|||
|
Important Ensure that The Conditions
for Running the Perform
the EVAP system Service Bay Test using a scan tool. Does the EVAP diagnostic
pass the Service Bay Test? |
-- |
Go to Diagnostic Aids |
||
|
Important The DTCs must be cleared
from the PCM in order to use the output control function on the scan tool.
Can
the value specified be obtained and held? |
10 in Hg |
|||
|
Important If an audible solenoid
click cannot be heard and DTC P0443 is not set, inspect the EVAP canister
purge solenoid circuits for high resistance.
Is
the vacuum measured on the gauge the same or more than the specified value? |
12 in Hg |
|||
Is
the vacuum measured on the gauge the same or more than the specified value? |
12 in Hg |
|||
Can
the specified value of vacuum be obtained and held? |
5 in Hg |
|||
Can
the specified value of vacuum be obtained and held? |
5 in Hg |
|||
Can
the specified value of vacuum be obtained and held? |
5 in. Hg. |
|||
Did
you find and correct the condition? |
-- |
|||
|
Important The following steps require
the EVAP Pressure/Purge Diagnostic Station J 41413 and
the Ultrasonic Leak Detector J 41416 . Always zero the EVAP
Pressure and Vacuum (in. H2O) gauges on the EVAP Pressure/Purge Diagnostic
Station J
41413 before proceeding with diagnosis.
Did
you find and repair the condition? |
-- |
|||
Did
you find and correct the condition? |
-- |
|||
|
Repair
the vacuum source to the EVAP Purge Solenoid Valve. Is the action complete? |
-- |
-- |
||
|
Important Inspect the EVAP Purge
Solenoid Valve and the purge line for carbon contamination. Refer to
Diagnostic Aids . Replace
the EVAP Purge Solenoid Valve. Refer to EVAP
Canister Purge Solenoid Valve Replacement . Is the action complete? |
-- |
-- |
||
|
Replace
the EVAP Vent Valve. Refer to EVAP
Vent Valve Replacement . Is the action complete? |
-- |
-- |
||
|
Replace
the EVAP Vapor Canister. Refer to EVAP
Canister Replacement . Is the action complete? |
-- |
-- |
||
|
Replace
the EVAP line from the EVAP Purge solenoid valve to the EVAP canister. Refer
to Fuel
Hose/Pipes Replacement (Chassis) . Is the action complete? |
-- |
-- |
||
Does
the Fuel Tank Pressure sensor indicate the actual amount of pressure in the
EVAP system? |
-- |
Go to Step
3 |
||
|
Replace
the Fuel Tank Pressure sensor. Refer to Fuel
Tank Pressure Sensor Replacement . Is the action complete? |
-- |
-- |
||
Does
the scan tool indicate that this test ran and passed? |
-- |
|||
|
Select
the Capture Info option and the Review Info option using the scan tool. Does
the scan tool display any DTCs that you have not diagnosed? |
-- |
Go to Applicable DTC |
System OK |