Code Definition

P0499 — Evaporative emission system vent control solenoid Circuit High

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

About P0499

P0499 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.

When P0499 is stored, the module has detected a signal or supply voltage higher than the expected operating range.

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 P0499 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 Powertrain Control Module (PCM) sets this code when it detects a higher-than-expected voltage in the evapourative emission (EVAP) system vent control solenoid circuit. This typically indicates a short to power, a faulty solenoid, or wiring issues preventing proper operation of the vent valve, which controls the release of fuel vapours from the EVAP system.

Quick Facts