OBD-II Code
P0499
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$110–$440
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
P0499 reports the EVAP vent valve control circuit voltage is high, meaning the circuit is open or shorted to power and the PCM cannot command the vent valve through its normal range.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Read the full diagnostic procedureP0499 reports the EVAP vent valve control circuit voltage is high, meaning the circuit is open or shorted to power and the PCM cannot command the ven…
P0499 reports the EVAP vent valve control circuit voltage is high, meaning the circuit is open or shorted to power and the PCM cannot command the vent valve through its normal range.
Cheapest diagnostic
confirm the vent valve is plugged in, then measure resistance across the valve terminals expecting 20-30 ohms on most platforms; an infinite reading confirms an open winding. Probe the harness at the connector with key on: you should see roughly 12V on the supply pin from the PCM, and the control pin should pulse to ground when the vent valve is commanded closed during EVAP testing. The expensive misdiagnosis is replacing the canister assembly when the fault is a $50 vent valve, a $5 connector repair, or a pinched harness from a recent suspension job.
Vehicle-specific patterns2003-2011 Honda Pilot/Odyssey/Ridgeline CVSV fails open from internal salt corrosion in northeast and midwest states; 2007-2013 Toyota Camry/Sienna V…
- 2003-2011Honda Pilot/Odyssey/Ridgeline CVSV fails open from internal salt corrosion in northeast and midwest states;
- 2007-2013Toyota Camry/Sienna VSV diaphragm tears at the vent valve, producing intermittent P0499;
- 2008-2014Subaru Outback/Forester vent valve harness gets pulled apart at the rear subframe during suspension service;
- 2009-2015Ford Flex/Taurus 3.5L vent valve connector backs out at the rear of the canister (TSB 14-0007).
Estimated repair$110 to $440.
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