Code Definition

P0442 — Evaporative Emission Control System leak Detected (small leak)

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About P0442

P0442 is a generic (obd-ii standard) powertrain diagnostic trouble code. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P0442 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The engine control module (ECM) sets this code when it detects a small leak in the EVAP system. The system is designed to prevent fuel vapours from escaping into the atmosphere by sealing and controlling vapour flow. The ECM monitors pressure changes in the system using the fuel tank pressure sensor during self-tests. If the pressure drop is slower than expected, indicating a small leak, this code is triggered.

Quick Facts