Er:17 is your Bosch’s Aquastop stepping in. A small float switch in the base pan rises if water collects there. When it thinks there’s a leak, the washer stops to protect your floor and cabinetry.

Unplug the washer before you touch a panel. Electricity + water isn’t a combo to experiment with.

Look inside the base pan

Remove the lower kick plate or service panel and see what the pan is telling you.
If there’s water, dry it out thoroughly. That’s only step one—the real work is finding where it came from. A loose clamp on a drain hose, a hairline crack in a bellows, a slow weep from the inlet valve, or even oversuds splashing into the pan can all pool enough to trip the float. Fix the source and the error clears once the pan stays dry.

If the pan is bone-dry, pay attention to the float. Sometimes a bit of lint, a cable tie tail, or a plastic chip wedges under it and leaves it stuck in the “leak” position. Gently move it up and let it drop; it should fall back freely. If it moves freely and the code persists, the float switch may have failed.

A couple of real-world tricks

After mopping, leave the panel off for a little while so humidity can escape; a damp pan can retrip the sensor. If you suspect a hidden puddle, tilt the machine slightly forward (carefully, with help) to coax water to the front edge where you can wipe it up. Glance at the external Aquastop inlet hose (the bulky head at the faucet): snug connections and no kinks. Slow seeps there love to masquerade as “mystery” leaks.

When replacement makes sense

If the float isn’t obstructed and the pan is dry, replacing the Aquastop/float switch assembly is usually the cleanest path. Order the part by your exact Bosch model number to avoid connector or mounting mismatches.

If the error snaps back immediately

That typically points to an intermittent leak that only shows during fill or drain, or to a wiring/switch fault. At that point, a technician can run a diagnostic cycle, pressure-test lines, and meter the switch so you’re not guessing or swapping parts twice.

Er:17 isn’t mysterious—it’s a water detection alert, or a stuck sensor pretending to be one. Kill the power, check the pan, fix any leak you find, free or replace the float switch, and give the cavity time to dry out. Follow that sequence and most machines go right back to work. If you’d rather not open panels—or the code keeps returning—call a pro and protect both the washer and your home.