P0442

Evaporative Emission System Monitoring - 0.020" (0.5mm) Diameter











Evaporative Emission System Monitoring - 0.040" (1.0mm) Diameter











DTC P0442
Evaporative control system - small leak detected Drive cycle C:Signal out of range - below minimum.

Possible causes by suggested order of priority:
- Leaking fuel filler cap.
- Leaking vent seal valve.
- Leaking tank protective valve.
- Faulty or missing hose clamp or poor seal.
- Poor seal on fuel tank pressure sensor.
- Fuel tank pressure sensor fault.

Leaking fuel filler cap.
CHECK THE FOLLOWING:
- Check fuel filler cap for any visible cause of leakage.
- Check fuel filler cap seal for contamination.
- Check fuel filler cap by substitution with known good unit
POSSIBLE FAULTS
- Faulty fuel filler cap.
- Fuel filler cap has poor seal.

Leaking vent seal valve.
CHECK THE FOLLOWING:
- Check purge cannister vent seal valve for any visible signs of leakage.
- Check vent seal valve for contamination with charcoal from purge can.
- Check vent seal valve by substitution with known good unit.
- Check vent seal valve attachment to purge cannister for soundness
POSSIBLE FAULTS
- Faulty purge cannister vent seal valve.
- Purge cannister vent seal valve contaminated.
- Purge cannister vent seal valve attachment to purge cannister leaking.

Leaking tank protective valve.
CHECK THE FOLLOWING:
- Check fuel tank with suitable pressure test equipment.
POSSIBLE FAULTS
- Faulty fuel tank pressure relief valve.

Faulty or missing hose clamp or poor seal.
CHECK THE FOLLOWING:
- All hose couplings and clamps in evaporative loss system.
POSSIBLE FAULTS
- Leakage at hose coupling to due faulty or missing clamp.

Poor seal on fuel tank pressure sensor.
CHECK THE FOLLOWING:
- Attachment of fuel tank pressure sensor to fuel tank.
- Substitute pressure sensor for known good unit.
POSSIBLE FAULTS
- Faulty seal at fuel tank pressure sensor.
- Faulty fuel tank pressure sensor.

Fuel tank pressure sensor fault.
CHECK THE FOLLOWING:
- Pressure sensor reads close to zero with filler cap removed.
- If equipment available pressurize the tank and check that the reading on the sensor is accurate.
POSSIBLE FAULTS
- Faulty fuel tank pressure sensor.