P0442
Evaporative Emission Control System Incorrect Purge Flow
Powertrain Emission Controls EVAP Purge Flow 🟡 Moderate — Fix within a week
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What This Actually Means
In plain language — no jargon

Your car's vapor recovery system isn't purging fuel vapors from the charcoal canister correctly, like a clogged straw preventing liquid from being drawn out. The engine control unit detected abnormal flow rates when it tried to pull stored fuel vapors back into the engine.

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Symptoms You May Notice
3 known symptoms for this code
Check Engine Light illuminated
Fuel smell near fuel door or under vehicle
No noticeable drivability issues in most cases
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors purge valve solenoid duty cycle and canister pressure via the fuel tank pressure sensor. It expects specific vacuum flow rates when the purge valve opens during cruise conditions. If actual flow deviates significantly from predicted values, the fault sets.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Purge Flow Rate 0.5–3.0 g/s during purge cycle Below 0.3 g/s or erratic fluctuation
Fuel Tank Pressure -7 to +10 inches H2O Exceeds +15 inches H2O when purge commanded
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Charcoal canister
Replace if canister is saturated, clogged, or has internal damage restricting vapor flow.
2
Purge valve solenoid
Clean or replace if valve is stuck closed, preventing vapor purge from the canister.
3
Purge control hoses
Inspect for cracks, pinches, or disconnection between canister, valve, and intake manifold.