Husqvarna Automower Error 004 — Front Loop Sensor

What Does This Error Mean?

Error 004 on a Husqvarna Automower means the front loop sensor cannot detect the boundary signal. Check that the charging station is powered on and the boundary wire is intact. The sensor itself rarely fails — almost always the wire or station is the cause.

Affected Models

Husqvarna Automower 305
Husqvarna Automower 315
Husqvarna Automower 315X
Husqvarna Automower 430X
Husqvarna Automower 450X

Common Causes

Boundary wire broken — usually near a corner or where it crosses the lawn surface
Charging station unpowered or unplugged
Boundary wire too far from the front sensor (mower stuck in a 'dead zone')
Failed front loop sensor (rare)

How to Fix It

Check the charging station.

Walk to the charging station and confirm the green LED is lit. If the LED is off, check the power adapter and the wall outlet. A dark LED means no boundary signal is being transmitted.
Look for a broken boundary wire.

Walk the entire boundary loop and look for breaks — typically near corners, where the wire crosses paths, or where lawn aerators may have caught it. A break is often visible as exposed copper or a snapped wire.
Check the wire connection at the charging station.

Confirm both ends of the boundary wire are firmly connected to the charging station terminals. A loose connection prevents the signal from reaching the wire loop.
Carry the mower closer to the boundary wire.

If error 004 occurred far from the boundary (mower stuck in the middle of the lawn), carry it close to the boundary and restart. The signal strength at the centre of large lawns can be marginal.
Re-spool a broken wire.

Cut both ends of the broken section, strip 1 cm of insulation, and join with a Husqvarna boundary wire connector (waterproof) or solder the ends and use heatshrink. Buried wire repairs need waterproofing — a bare twist will corrode and fail.

Frequently Asked Questions

Why does Husqvarna error 004 only happen in one part of the lawn?

If error 004 only appears in a specific spot, the boundary wire signal is weakest there — usually because the wire path passes too far from that area. Adding a guide wire or rerouting the boundary can help.

How do I find a break in the Automower boundary wire?

Switch to wire-break detection mode in the menu (Settings > Loop Wire > Find break). Walk the wire with the mower in detection mode — the mower beeps faster as it approaches the break. This narrows the location to within 1–2 metres.