P0442 code meaning
EVAP System Leak Detected (small leak)
Powertrain system Generic code P04xx codes Check engine light
What P0442 means
The evaporative emission (EVAP) system stores fuel vapour from the tank in a charcoal canister; a purge valve lets the engine draw it off, and a vent valve opens the canister to fresh air. P0442 reports a small leak; what size that means depends on the maker. Ford detects 0.040 in (1 mm) with the engine running: the vent valve closes, engine vacuum pulls the tank down, the purge valve closes and a pressure rise above 2.5 inH2O in 15 s sets the code (0.020 in is P0456). GM uses the natural pressure change after switch-off for 0.020 in and averages several tests. Pump systems at VW and Audi compare against a reference leak. A worn or loose fuel cap is the most common cause.
P0442 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.2 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P0442
- Check engine light on
- Possibly slight fuel smell
- Readiness or emission inspection not passed
- No change in driving
Common causes of P0442
- Most likelyFuel cap seal worn, wrong or not clicked in
- Most likelyCracked or porous EVAP hoses or leaking connections
- PossiblePurge or vent valve does not seal
- PossibleLeak detection pump itself leaking (VW/Audi)
- Less likelyFiller neck corroded, tank or sender seal leaking
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
EVAP systemFuel capEVAP hosesFuel tank pressure sensor
What each part of P0442 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 42 | The exact fault in that area. |
What to do next
- Note P0442 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0442
What does P0442 mean?
P0442 means "EVAP System Leak Detected (small leak)". The evaporative emission (EVAP) system stores fuel vapour from the tank in a charcoal canister; a purge valve lets the engine draw it off, and a vent valve opens the canister to fresh air. It is a generic code, so it means the same on every make.
Is it safe to drive with P0442?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0442 fail an emissions test?
Yes, it can. P0442 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0442 to fix?
Difficulty: medium. A typical repair takes 0.2 to 3 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0442 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.