P0498: EVAP vent circuit low is a power-stage grounding report

P0498 is the low-circuit fault for the evaporative-emissions vent valve. In this GM monitor the controller receives a power-stage report of a short to ground. The information arrives in a CAN message, but the reported failure concerns the vent electrical output.

The electrical report has its own qualification

Ignition must be on, the status must satisfy a two-second interval, and the code uses two-trip reporting. The document also refers to enable and inhibit tables. A vent command performed when those conditions are not met is not automatically a complete reproduction of the monitor.

This code should not be treated as a small vapor leak simply because it belongs to the EVAP system. Nor does its CAN transport make it a lost-communication code. The specific evidence is the received short-to-ground status.

Preserve module-level detail

If diagnostic equipment exposes the EVAP power-stage status, retain it along with the main controller’s code. That can establish which output diagnosis was reported and separate it from open-load or short-to-supply cases.

The summary does not locate the grounding condition or prove that the vent valve itself is defective. Circuit and module information for the actual vehicle are needed to distinguish the load, harness and driver. A replacement decision should follow that localization, not a generic leak-system checklist that never examines the electrical condition reported here.

Source and applicability

This explanation covers the cited GM monitor, not every vehicle carrying this code. The application-matrix filename does not resolve cleanly to this file, so no model or engine fitment is assigned. GM diagnostic table, PDF page 694.