P0442 - EVAP System Leak Detected (small leak)
P0442 is a generic powertrain diagnostic trouble code indicating EVAP System Leak Detected (small leak). It relates to the Auxiliary Emission Controls system.
DTC Breakdown (SAE J2012)
| System | Powertrain (P) |
| Type | Generic |
| Subsystem | Auxiliary Emission Controls |
| Fault Index | 42 |
| Standard | SAE J2012 / ISO 15031-6 |
What does diagnostic code P0442 mean?
The EVAP system has detected a small fuel vapor leak, meaning gasoline vapors are slowly escaping from the fuel tank or evaporative emission lines.
Severity Level & Driveability Details
Severity: Low
It has no effect on engine performance or driveability. It only affects emissions.
Common Symptoms of P0442
- Check engine light illuminated on the dashboard due to a small EVAP leak.
- Occasional faint fuel smell.
Typical Causes for P0442
- Loose, dirty, or cracked gas cap gasket (most common).
- Small crack in EVAP vacuum lines or carbon canister.
- Failed purge or vent control valve.
Diagnostic and Troubleshooting Steps
Inspect the gas cap. If the cap is tight and clean, perform a smoke test of the EVAP system. Pressurize the fuel tank and EVAP lines with diagnostic smoke to locate the leak.
Typical Repairs and Fixes
- Tightening or replacing the gas cap.
- Replacing cracked EVAP hoses.
- Replacing the purge or vent solenoid.
Sensor Location & Parts Involved
The EVAP canister and vent valve are located underneath the vehicle near the fuel tank; the purge valve is in the engine bay.
Clearing Code & Recurrence
Clear the code with a scan tool to reset the monitors and perform a verification drive.
Emissions & Smog Inspection Impact
Allows raw fuel vapors (hydrocarbons) to vent into the atmosphere, causing smog check failures.
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Related Diagnostic Codes
Sources & References
This diagnostic guide is compiled and verified against the following authority sources:
- EPA EVAP Standards
- CARB OBD II regulations
Frequently Asked Questions about P0442
What does the EVAP control system small leak code P0442 mean?
The Evaporative Emission Control (EVAP) system logged P0442 after detecting a small leak in the sealed fuel vapor loop.
Is it safe to drive with the EVAP control system small leak code P0442 active?
Yes, an EVAP fault poses no danger to vehicle function.
How much does it cost to repair a EVAP control system small leak code P0442 fault?
A new gas cap is $15-$30, while vent or purge solenoids run $150-$300 and carbon canisters cost $300-$500.
What are the common causes of the EVAP control system small leak code P0442?
Trigger conditions for the EVAP control system small leak code P0442 include: Loose, dirty, or cracked gas cap seal., Hairline cracks in the EVAP canister or vacuum lines., Failed EVAP vent control valve or purge valve..
Can I clear the check engine light for EVAP control system small leak code P0442?
Clear the code with a scan tool to reset the monitors and perform a verification drive.
Will the EVAP control system small leak code P0442 cause an inspection failure?
Allows raw fuel vapors (hydrocarbons) to vent into the atmosphere, causing smog check failures.