Aston Martin diagnostic trouble code
P0442: Evaporative Emission System Leak Detected (small leak)
Use this reference to understand the recorded condition, confirm the available V8 Vantage or DB9 manual coverage, and follow the documented diagnostic checks before replacing parts.
- Code family
- Powertrain
- Vehicle system
- Emissions and EVAP
- Manual coverage
- DB9
- Warning-lamp status
- DB9: MIL
What Aston Martin code P0442 means
Evaporative Emission System Leak Detected (small leak)
DB9 preliminary diagnostic manual · section 2-90
Manufacturer fault-analysis procedure
Manual fault definition
P0442 - Unable to hold tank vacuum (small leak)
Cautions and notes
NOTE: The integrity of the vapour recovery system is
checked by closing the canister vent valve, opening the
vapour management valve and applying a vacuum
from the inlet manifold. When the fuel tank vacuum is
at an appropriate level, the VMV is closed.
The vacuum in the closed vapour recovery system may
then be monitored using the fuel tank pressure transducer.
The system checks for small leaks (P0442) or for gross
leaks (P0455).
CAUTION: This code is generated only in the Primary Powertrain Control Module (PCM). Check
that you are working on the primary half of the
engine.
checked by closing the canister vent valve, opening the
vapour management valve and applying a vacuum
from the inlet manifold. When the fuel tank vacuum is
at an appropriate level, the VMV is closed.
The vacuum in the closed vapour recovery system may
then be monitored using the fuel tank pressure transducer.
The system checks for small leaks (P0442) or for gross
leaks (P0455).
CAUTION: This code is generated only in the Primary Powertrain Control Module (PCM). Check
that you are working on the primary half of the
engine.
Test sequence and decision path
1. Connect the WDS and read the logged DTCs.
If P0443, P0446 - P0457 are logged, rectify these
problems first. Return to this procedure only if
P0442 is logged again after clearing these codes.
2. Check the evaporative loss system for obvious
defects which could cause a vacuum leak:- e.g.
Loose or defective fuel filler cap or seal
Loose vapour connections at the canisters
Loose connections in the vapour recovery lines in
the engine bay.
If no defects are identified, go to step 3.
If any defects are identified, service as necessary
and run the KOER test to ensure that the problem
is resolved.
3. Run the WDS Evaporative Emission Leak Test.
If a leak is detected, go to step 4.
If no leak is detected, clear the P0442 code and
run a road test to confirm that the problem is no
longer present.
4. WARNING: Do not exceed the maximum pressure specified in this step. Excessive pressure can
cause damage in the fuel system.
With the fuel filler cap securely in place, connect
an evaporative loss system tester to the schreader
valve near the primary carbon canister.
Temporarily plug the vent pipe from the canister
vent valve to atmosphere.
Pump a pressure of 14.0±1 in H
2
O (34.8 kPa) into
the fuel system. Hold the pressure and monitor
the gauge reading.
If the system cannot hold the pressure for at least
one minute, go to step 5.
If the system does hold the pressure for one
minute, the problem is forward of the vapour
management valves. Go to step 5.
5. Use the ultrasonic leak detector to locate the leak
by sound. Service the system as necessary.
If the leak cannot be detected, go to step 6.
Run a Soak and Road Test as detailed below to
ensure that the problem is resolved.
6. Remove the vapour recovery tubes from the inlet
manifolds. Connect the evap loss system tester to
one tube.
Pressurise the tube to 14.0±1 in H
2
O (34.8 kPa)
and monitor the gauge reading for one minute. If
the pressure drops, use the ultrasonic leak detector to locate the leak by sound. Service the system
as necessary.
Reassemble the system and run a Soak and Road
Test to ensure that the problem is resolved.
If no leak is detected, the fault is not present at
this time and testing is complete. Clear logged
DTCs.
Soak and Road Test
The vacuum tests are only run during a drive cycle
after the ignition has been switched off for more
than 5 hours. If less than 5 hours have elapsed, the
vacuum tests are omitted from the drive cycle.
Leave the vehicle parked overnight (or more than
5 hours) and then run a road test which must include steady running at over 40 m.p.h. for more
than 5 minutes.
Open the corresponding manual page for wiring diagrams and figures
If P0443, P0446 - P0457 are logged, rectify these
problems first. Return to this procedure only if
P0442 is logged again after clearing these codes.
2. Check the evaporative loss system for obvious
defects which could cause a vacuum leak:- e.g.
Loose or defective fuel filler cap or seal
Loose vapour connections at the canisters
Loose connections in the vapour recovery lines in
the engine bay.
If no defects are identified, go to step 3.
If any defects are identified, service as necessary
and run the KOER test to ensure that the problem
is resolved.
3. Run the WDS Evaporative Emission Leak Test.
If a leak is detected, go to step 4.
If no leak is detected, clear the P0442 code and
run a road test to confirm that the problem is no
longer present.
4. WARNING: Do not exceed the maximum pressure specified in this step. Excessive pressure can
cause damage in the fuel system.
With the fuel filler cap securely in place, connect
an evaporative loss system tester to the schreader
valve near the primary carbon canister.
Temporarily plug the vent pipe from the canister
vent valve to atmosphere.
Pump a pressure of 14.0±1 in H
2
O (34.8 kPa) into
the fuel system. Hold the pressure and monitor
the gauge reading.
If the system cannot hold the pressure for at least
one minute, go to step 5.
If the system does hold the pressure for one
minute, the problem is forward of the vapour
management valves. Go to step 5.
5. Use the ultrasonic leak detector to locate the leak
by sound. Service the system as necessary.
If the leak cannot be detected, go to step 6.
Run a Soak and Road Test as detailed below to
ensure that the problem is resolved.
6. Remove the vapour recovery tubes from the inlet
manifolds. Connect the evap loss system tester to
one tube.
Pressurise the tube to 14.0±1 in H
2
O (34.8 kPa)
and monitor the gauge reading for one minute. If
the pressure drops, use the ultrasonic leak detector to locate the leak by sound. Service the system
as necessary.
Reassemble the system and run a Soak and Road
Test to ensure that the problem is resolved.
If no leak is detected, the fault is not present at
this time and testing is complete. Clear logged
DTCs.
Soak and Road Test
The vacuum tests are only run during a drive cycle
after the ignition has been switched off for more
than 5 hours. If less than 5 hours have elapsed, the
vacuum tests are omitted from the drive cycle.
Leave the vehicle parked overnight (or more than
5 hours) and then run a road test which must include steady running at over 40 m.p.h. for more
than 5 minutes.