Hydrogen in a fuel cell is vented and purged with a fail-closed valve using stored energy (e.g. from a capacitor) when a diagnostic parameter is outside of an acceptable operating range. The valve closes after the stored energy has depleted. A safety switch in the relay circuit of the solenoid switch (or solenoid valve) is also grounded in computer-implemented shutdowns. Benefits from the invention include use of air-compatible catalysts, minimized parasitic losses to power output, minimized contamination of fuel cell internal surfaces after venting, minimized risk of explosive mixture buildup, and efficient operation.