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Q: P0442

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We have code P0442 keep coming up we changed the gas cap but the still keeps saying tighten gas cap could we have a small leak in the evap system or should we try to replace the gas cap again?

My car has 120000 miles.
My car has an automatic transmission.

As you may already know, this may be related to a faulty or leaking gas cap, however this can also be related to several other factors such as the following:

  • A non-conforming gas cap (i.e. not factory/original brand)
  • A small leak/hole in a fuel vapor hose/tube
  • Other small leak in EVAP system
  • Faulty vent o-ring seal
  • Defective vent valve
  • Defective purge valve
  • Defective leak detection pump

To avoid any unnecessary repairs, I would suggest having a professional from YourMechanic come to your home to take a closer look at your vehicle’s evaporative emissions system and further diagnose your trouble code.

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