CarSpecFix
OBD-II trouble code

P0442: Evaporative Emission System Small Leak Detected, causes & can you keep driving?

Quick answer

What it means
Evaporative Emission System Small Leak Detected[1]
Wording from GM Service Bulletin 21-NA-124 (EVAP P0442/P0455 diagnostic tips), p.1
Can I keep driving?
It is important to note that an illuminated dashboard light, as described here, is intended to inform the driver of the need for service, NOT of the need to stop the vehicle. However, service should be sought as soon as possible.[2]
U.S. EPA Fact Sheet EPA 420-F-97-003 (May 1997), Frequently Asked Questions About On-Board Diagnostics, p.2 · applies to all OBD-II vehicles
Only for the specific vehicles listed — not general advice:
Toyota only If the malfunction indicator lamp comes on while driving First check the following: Is the fuel tank empty? If it is, fill the fuel tank immediately. Is the fuel tank cap loose? If it is, tighten it securely. The light will go off after several driving trips. If the light does not go off even after several trips, contact your Toyota dealer as soon as possible.[3]
Toyota only When "Check Fuel Cap" is displayed on the multi-information display: The fuel tank cap may be unfastened or loose. Turn the engine switch off, check the cap and tighten it securely.[3]
Toyota only Malfunction indicator lamp ... Indicates a malfunction in: The electronic engine control system; The electronic throttle control system; or The electronic automatic transmission control system → Have the vehicle inspected by your Toyota dealer immediately.[3]
What this code alone can’t tell you
Steady light: get the car serviced as soon as possible, but this is not a reason to stop driving.[2]
U.S. EPA Fact Sheet EPA 420-F-97-003 (May 1997), Frequently Asked Questions About On-Board Diagnostics, p.2 · applies to all vehicles
Check first: Tighten the fuel cap until it clicks, then drive a few trips and see whether the light goes out on its own.[2]
What a repair will cost varies by vehicle, region and shop, and no official source publishes a price for a single fault — so this site does not estimate one. We publish only figures we can trace to an official document; for the federal statistics that do exist, see NHTSA statistics.
Shop visit or check it yourself first?
Tighten the fuel cap until it clicks, then drive a few trips and see whether the light goes out on its own.[2]
U.S. EPA Fact Sheet EPA 420-F-97-003 (May 1997), Frequently Asked Questions About On-Board Diagnostics, p.3
Last verified 2026-10-15Report a data error

Possible causes

Each cause comes from a manufacturer document and applies to the models listed. Your vehicle may differ.

  1. GM's tech tip (GM Service Bulletin 21-NA-124 (EVAP P0442/P0455 diagnostic tips), p.1) [1]
    Purge valve stuck open
  2. GM's tech tip (GM Service Bulletin 21-NA-124 (EVAP P0442/P0455 diagnostic tips), p.1) [1]
    Canister vent valve stuck open
  3. GM's tech tip (GM Service Bulletin 21-NA-124 (EVAP P0442/P0455 diagnostic tips), p.1) [1]
    EVAP system not sealed / purge lines not properly connected

NHTSA statistics

How often P0442 shows up in the federal complaint and recall databases.

Complaints that mention P0442
53
out of 1,626,788 complaints in NHTSA's database[4]
Recall campaigns that cite P0442
0
out of 30,378 campaigns since 1967 — recall summaries describe defects in consumer terms and do not list diagnostic codes[5]

How this is counted: code counted when it appears in the complaint description (CDESCR) for complaints, or in the recall component/defect/consequence/corrective-action text for recalls; unique ODINO per complaint and unique CAMPNO per recall. Complaints are voluntary and unverified — a mention is not proof that P0442 caused the problem. Neither file contains repair-price data, which is why this site does not publish cost estimates.

Sources

  1. GM Service Bulletin 21-NA-124 (EVAP P0442/P0455 diagnostic tips), p.1, retrieved 2026-10-15
  2. U.S. EPA Fact Sheet EPA 420-F-97-003 (May 1997), Frequently Asked Questions About On-Board Diagnostics, p.2, retrieved 2026-10-15
  3. 2022 Toyota Camry Owner's Manual OM06244U, p.533, retrieved 2026-10-15
  4. NHTSA ODI complaint flat file (FLAT_CMPL.zip), retrieved 2026-10-20
  5. NHTSA ODI recall flat file (FLAT_RCL_POST_2010.zip), retrieved 2026-10-20

General information from manufacturer documents, not professional mechanical advice. See Data sources.