P0442 on a Ford

What is different about P0442 on a Ford?

Ford's sensitive NVLD detection method means the medium leak threshold behind P0442 often catches issues at an earlier stage of wear than it would on a less sensitive system.

Patterns documented on Ford vehicles

Partially degraded gas cap seal: A gas cap seal that has degraded enough to leak more than the small-leak threshold but not enough to reach the large-leak threshold is a documented cause of P0442 on Ford vehicles specifically because of how sensitive the NVLD system is to leak size.

Filler neck hardware cracks: Small cracks in fuel filler neck hardware, distinct from the hose itself, are a documented contributor to medium leak codes on some Ford vehicles.

What to check first on a Ford

The order below narrows the generic P0442 list down to what is worth checking first on this make. It is a starting order, not a diagnosis: patterns are generation specific and a vehicle outside those generations may have none of them.

Check in this order

• Inspect the gas cap seal closely for partial wear
• Inspect the fuel filler neck hardware for small cracks
• Inspect the NVLD module and hoses for a leak of intermediate size
• Use a smoke test if available to help pinpoint the leak

The generic picture behind P0442

The computer periodically seals the evaporative system and watches for a pressure or vacuum change over time to test for leaks. This code sets when that test finds a leak small enough to fall into the mid-size category the manufacturer defines, larger than the smallest detectable leak but smaller than an obvious opening such as a loose cap.

Everything on the main P0442 page still applies here. This page narrows the cause list to the patterns documented on Ford vehicles, it does not replace the underlying definition.

The generic version of this code

• P0442 on any vehicle