North American Fault Code
Free · no signupP0442 / P0455
"Check Gas Cap" message; Fuel smell around the rear of the vehicle; Failed emissions.
System
Not specified
Symptom
"Check Gas Cap" message; Fuel smell around the rear of the vehicle; Failed emissions.
Diagnosis & fix steps
EVAP System Leak Detected (Small or Large).
LOGIC: The PCM pulls a vacuum on the fuel tank and monitors for a pressure drop. A drop indicates a leak to the atmosphere.
ACTION: 1. Inspect gas cap seal.
2. Smoke test the EVAP lines.
3. Test Purge and Vent solenoid operation.
FIX: Tighten/replace gas cap; replace Purge Solenoid (common on GM); replace rusted filler neck.
Red Seal field insights
On Ford vehicles with "Capless" fueling, the seal often gets dust in it. Use a funnel to manually open and close the flap several times to clear the debris before clearing the code.
Same code keeps coming back?
That's a program problem, not a part problem. Book a 30-minute uptime review with Grant, a Red Seal Heavy Duty Technician.
Read before you touch anything
- This is general reference information, not a repair manual. It is for trained, qualified technicians.
- Fault codes, meanings and procedures vary by model, serial number and software version. Confirm the code and the procedure against the manufacturer's service manual before acting.
- Follow the OEM service manual, torque specs and your site's safety procedures: lockout/tagout, block raised equipment, relieve hydraulic, fuel and air pressure, and let hot systems cool.
- You use this information at your own risk. Adventure Mechanical and AM Fleet Integrity accept no liability for damage, injury, downtime or loss arising from its use.
- Not affiliated with or endorsed by any manufacturer. Brand names are used only to identify the equipment a code applies to.
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