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Enter a 5-character code such as P0420, P0301, or P0457.

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Codes starting with P are engine and transmission, B are body, C are chassis, and U are network communication. A 0 as the second character means a generic code shared by all makes; a 1 means a manufacturer-specific code, so its meaning depends on your brand.

A steady check engine light usually means get it checked soon. A flashing check engine light means an active misfire: reduce speed and stop driving as soon as it is safe.

That doesn't look like an OBD-II code

A valid code is one letter (P, B, C, or U) followed by four characters, for example P0420.

P0442 EVAP system small leak detected

Can I drive with P0442?

Drive

Safe to keep driving normally. Fix it when convenient.

It only affects fuel-vapor emissions, not how the engine runs. Because the leak is small, it can take several drives for the code to set or come back, and the light stays on until the system passes its test.

What does P0442 mean?

The fuel vapor system found a small leak, roughly the size of a pinhole. The computer seals the system and watches whether its pressure or vacuum holds. If the reading fades slightly faster than it should, the computer sets this code.

What causes P0442?

A worn gas cap seal is the cheapest thing to check. Small cracks in hoses and valves that do not seal fully are the other usual causes.

  1. Worn gas cap seal
  2. Small crack in an EVAP hose
  3. Purge or vent valve not sealing
  4. Leaking fuel filler neck

How much does it cost to fix P0442?

$0 – $500

Start with the gas cap ($15–$60). A shop smoke test to find the leak costs $100–$150. Small leaks are hard to see, so the smoke test is usually worth it once a new cap has not fixed the problem.

What are the symptoms of P0442, and how can I confirm it?

There are almost never driving symptoms. Tighten the cap until it clicks and inspect its seal. Then check the visible EVAP hoses near the filler neck and charcoal canister for cracks. If nothing shows, a smoke test finds the leak. A valve code such as P0446 alongside it suggests that valve is not sealing.

Will P0442 fail an emissions test, and should I clear it?

It fails any OBD-II based inspection while the light is on, and the EVAP monitor runs only under certain fuel-level and temperature conditions. After checking the cap, clear the code and drive normally for several days. If P0442 returns, the leak is elsewhere. Avoid clearing it right before an inspection.

Confirm the code yourself

A low-cost scanner lets you read the code, clear it, and see if it comes back before paying for a diagnosis.

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