Evaporative emission system leak detected — small leak
P0442 means the controller detected a small loss of vacuum, pressure, or sealing performance in the evaporative-emissions system during its leak test. It does not identify a failed part or establish a repair price by itself.
Conditions that can produce P0442
These are diagnostic branches, not a ranked shopping list. Testing order depends on the exact vehicle and failure scene.
- Loose, damaged, or incorrect cap/seal
- Small hose, fitting, canister, tank, or pump seal leak
- Purge or vent valve not sealing
- Leak-detection pump or pressure sensor problem
- Corrosion, debris, or temperature/fuel-level test issue
What to inspect next
- Stop for strong fuel odor or visible leakage
- Inspect cap and accessible vapor plumbing without creating sparks
- Use an approved low-pressure smoke/leak method
- Command or bench-test valves only with exact safe procedures
What strengthens the answer
Prove what changed
Preserve the pre-repair record, document exactly what changed, and repeat the relevant operating condition safely. Confirm that current or pending faults do not return, review permanent-code and readiness state where applicable, and state which tests or modules remained unavailable.
P0442 questions
What does P0442 mean?
The controller detected a small loss of vacuum, pressure, or sealing performance in the evaporative-emissions system during its leak test.
Does P0442 identify the broken part?
No. A loose cap can be one cause on capped systems, but seals, hoses, valves, the canister, tank components, leak-detection hardware, and test conditions all matter. Fuel vapor requires fire-safe procedures. Confirm the exact vehicle definition and test the relevant branches before ordering a part.
Is it safe to drive with P0442?
Driving risk depends on the symptoms, warning-lamp behavior, and affected system. Stop for unsafe operation, a flashing warning lamp, smoke, fuel odor, overheating, braking or steering changes, or electrical heat.
How much does P0442 cost to repair?
The code alone cannot produce a defensible repair price. Cost depends on the confirmed cause, exact vehicle, parts choice, labor time, local labor rate, tax, supplies, and whether related damage is present.
What should I record before clearing P0442?
Record the reporting module, stored or pending status, freeze-frame data, readiness state, related codes, symptoms, battery voltage, and unavailable evidence. Clearing first can erase the most useful failure-scene context.
This page explains a commonly standardized code at a general level. Confirm the exact definition, module, status, test conditions, thresholds, wiring, and service process for the vehicle using current official information.
See how this page earns trust.
These links are primary-source starting points for the page's scope. They do not replace the current manufacturer procedure, wiring, specification, or service information for a specific vehicle.
Publisher
ScanWrench Editorial is the working byline for this library. Joshua Black, founder and publisher, is responsible for publication decisions, disclosures, and corrections.
A reviewed date means an editorial scope and safety check. It is not an ASE credential, OEM authorization, or vehicle-specific repair approval.
Primary sources
- SAE J2012 — Diagnostic Trouble Code DefinitionsSAE International · Standardized DTC structure, definitions, and manufacturer-controlled ranges.
- SAE on-board diagnostics standards indexSAE International · Primary standards family for regulated OBD services, identifiers, and transport context.
- OBD frequently asked questionsU.S. Environmental Protection Agency · Public explanation of regulated emissions diagnostics and the malfunction indicator light.
Revision history
- Reviewed edition: claim boundaries, safety language, internal links, and cited source scope checked.
No material correction has been recorded after this edition. If that changes, the correction and review date will be listed here.
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