Code
P0497
Generic
P — Powertrain
EVAP System Low Purge Flow
Views:
UK: 14
EN: 32
RU: 30
AI status
Completed
Completed
100%
Causes
- Stuck or failed EVAP purge solenoid (stuck closed or intermittent)
- Blocked, kinked, or collapsed purge hose/line between canister and intake
- Clogged charcoal canister or internal restriction
- Faulty or stuck EVAP vent/vent control valve (not allowing proper flow)
- Large vacuum leak elsewhere in intake reducing purge flow
- Wiring or connector fault to purge valve (open, short, or high resistance)
Symptoms
- Check Engine Light (MIL) illuminated
- Failed EVAP purge monitor or readiness test
- Possible fuel vapor odor at fuel tank (less common)
- No driveability symptoms in many cases, but occasional rough idle or hesitation if purge stuck open/closed intermittently
What to check
- Scan for DTCs and freeze frame data; note fuel level, engine temp, and purge request percentage when code set
- Verify ability to command purge valve ON/OFF with a scan tool and observe response
- Measure purge valve coil resistance and inspect connector for corrosion or damage
- Visually inspect purge and vent hoses for kinks, restrictions, crushed sections or disconnections
- Perform a smoke test of the EVAP lines to reveal leaks or blockages
- Manually apply vacuum to purge port (or use a hand-held vacuum pump) to confirm flow into intake while valve is commanded open
Signal parameters
- Purge valve coil resistance (ohms) — compare to spec (typical solenoids often 20–40 Ω but check vehicle spec)
- Commanded purge duty cycle / ON command from PCM (%) or ON/OFF status
- Measured purge flow rate (L/min) if flow meter available
- Manifold vacuum at purge port (inHg or kPa) during commanded purge
- Vent valve open/closed status and vent line pressure
- Fuel tank pressure sensor readings and EVAP monitor PIDs from scan tool
Diagnostic algorithm
- Retrieve and record DTCs, freeze-frame data, and readiness status. Note conditions when code set (fuel level, ambient temp, engine temp).
- Visually inspect EVAP purge and vent hoses, connections, and charcoal canister for damage, collapse or restriction.
- With a scan tool, command the purge valve ON and OFF. Listen for solenoid clicking and observe commanded PID. If no click, check power and ground at connector.
- Measure purge valve coil resistance and compare to manufacturer spec. Repair or replace if out of range.
- With valve commanded open, apply vacuum to purge line (hand pump) or use a flow meter to confirm flow into intake. If no flow, isolate between valve, canister, and intake to find restriction.
- Perform smoke test on EVAP lines and canister to locate internal blockages or leaks and to verify vent valve operation.
- Inspect/replace vent control valve if it is stuck closed or not venting — a closed vent can prevent purge flow.
- If hoses, valves and canister check good but low flow persists, inspect wiring and PCM outputs for correct voltage/duty cycle. Repair wiring/connectors as needed.
- After repairs, clear codes and perform drive cycle/EVAP monitor to confirm P0497 does not return.
Likely causes
- Purge solenoid failed or not actuating
- Clogged or restricted purge hose or canister
- Vent valve not operating (stuck closed) preventing flow path
Fault status
Status
PCM detected lower-than-expected EVAP purge flow during a commanded purge event. This indicates insufficient vapor flow from the EVAP system to the intake and sets MIL.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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