Cleaning Autopilot Sensors: Compass and Gyro

Why sensor cleaning matters

Your autopilot's heading sensor, often a compass and gyro in one unit, tells the system which way the boat is pointing. If that sensor is dirty, covered, or affected by nearby magnetic fields, the autopilot may steer poorly or not at all. Keeping the sensor clean and unobstructed is a simple way to help your system work as intended.

The heading sensor is the heart of the autopilot's sense of direction. It works with the control head and the drive unit to keep the boat on the course you set. For a detailed look at the types of sensors used in autopilots, see our guide on heading sensor types.

This article explains how to clean the heading sensor and other sensors on your autopilot in general terms. It does not replace the maker's manual. For specific steps, always follow the manual and, if you are unsure, ask a qualified installer.

Which sensors need cleaning

Most autopilots rely on a heading sensor that combines a compass and a gyro. Some systems also use a rudder reference unit that tells the autopilot the rudder's position. These are the parts you might clean.

The heading sensor is often a small, sealed unit mounted away from magnetic interference. The rudder reference unit is usually attached to the steering system. Both can collect dust, salt, or moisture over time.

Other parts of the autopilot system, such as the control head or the drive unit, also benefit from occasional cleaning, but this article focuses on the sensors. For general maintenance of the entire system, see our article on autopilot system maintenance.

• Heading sensor (compass and gyro)
• Rudder reference unit
• Control head (if it has a sensor)
• Connectors and cables near the sensors

How to clean the sensors

Start by turning off power to the autopilot. Use a soft, dry, lint-free cloth to gently wipe the outside of the sensor. Do not use water, solvents, or spray cleaners, as they can damage the electronics or leave residue.

If there is visible salt or grime, you can slightly dampen the cloth with fresh water, but be careful not to let moisture enter any openings. Dry the area thoroughly before restoring power.

For connectors and cables, inspect them for corrosion or loose connections. You can clean the connector pins with a dry cloth or a specialized contact cleaner, but only if the maker's manual allows it. Never force a connector apart.

If your sensor is mounted in a location that is hard to reach, consider using a soft brush or a can of compressed air to remove dust. Avoid blowing air directly into the sensor's openings, as that can push debris deeper.

What to avoid

Do not disassemble the sensor. Heading sensors are sealed units; opening them can void the warranty and ruin the calibration. Do not use abrasive pads, brushes, or harsh chemicals.

Avoid placing magnets or magnetic tools near the sensor. Magnetic interference can affect the compass reading. Also, do not move the sensor unless the manual says you can, as its position is part of the setup.

Never use a pressure washer or a hose to clean the sensor. Water can seep into the housing and cause corrosion or short circuits. Similarly, avoid cleaning products that contain ammonia or alcohol, as they can degrade the plastic and seals.

If you are unsure whether a particular cleaning method is safe, stop and consult the maker's manual or a qualified installer. For more on how sensors work in autopilots, see our article on sensor requirements.

When to call a professional

If cleaning does not solve the problem, or if you notice signs of damage like cracks, water inside, or loose mounting, contact a dealer or qualified installer. They have the tools and knowledge to diagnose issues without risking further damage.

The maker's manual will have specific cleaning and maintenance instructions. If you do not have the manual, find it on the maker's website or ask the seller.

Sometimes a sensor issue is not about cleaning but about calibration. If the autopilot holds course poorly even after cleaning, it may need a calibration update. Our article on calibration importance explains why this matters.

Maintenance tips

Regularly inspect the sensor area for dust, salt, or moisture. Keep the area around the sensor clear of gear that could block airflow or cause magnetic interference.

If your boat sits for long periods, consider covering the sensor or the helm to reduce dust accumulation. Always check the sensor after a rough trip or if the autopilot behaves oddly.

When you install a new sensor or replace an existing one, the position and orientation are critical. Follow the maker's instructions and, if possible, have a professional handle the mounting. For more on installation planning, see our article on installation planning.

Sensor location and access

The heading sensor is usually mounted in a place that is out of the way, such as inside a console, behind a panel, or in a mast for sailboats. Access may require removing a cover or reaching into a tight space.

Before you start, make sure you have good lighting and a comfortable working position. Use a headlamp if needed. Take care not to drop tools or damage nearby wiring.

If the sensor is in an area that is exposed to weather, check the seals and gaskets for wear. A worn seal can let moisture in, which is a common cause of sensor failure. Replacing a damaged seal is a task for a professional if you are not comfortable doing it yourself.

Cleaning the rudder reference unit

The rudder reference unit (sometimes called a rudder feedback unit) tells the autopilot the rudder's position. It is often mounted near the steering gear and can collect dirt and moisture.

Clean the outside of the unit with a dry cloth, and inspect the linkage for any signs of wear or corrosion. The linkage should move freely without binding. If you find stiffness, do not force it; apply a small amount of a suitable lubricant only if the maker's manual recommends it.

For more on how the rudder reference fits into the system, see our guide on rudder feedback sensors.

Maker-specific notes

Different makers have different designs. For example, Raymarine's Evolution series uses a sealed 3D heading sensor, while Furuno's NavPilot systems often work with a separate heading source like a compass or a GPS compass. Always check the product documentation for your specific model.

On the Raymarine autopilot page, the company describes the sensor as the "autopilot central processor and 3D heading sensor" at the heart of the Evolution system. This indicates that the sensor is a critical, sealed component, and cleaning should be limited to the exterior.

Furuno's NavPilot 300, as shown on its product page, requires a compatible heading source such as the PG700 or SC33. These external sensors also need gentle cleaning and proper placement. If you are unsure what sensor your system uses, refer to the maker's manual or a dealer.

What to pick for your situation

Questions

Can I use water to clean the heading sensor?

It is best to use a dry cloth. If you must remove salt, slightly dampen the cloth with fresh water, but avoid letting moisture enter the sensor. Dry thoroughly before powering on.

Should I open the sensor to clean inside?

No. Heading sensors are sealed units. Opening them can damage the electronics and void the warranty. If you suspect internal issues, contact a professional.

How often should I clean the sensors?

There is no set schedule. Inspect them regularly, especially after long trips or if the boat is stored outdoors. Clean when you see dust, salt, or grime.

What if cleaning doesn't fix the autopilot?

If the autopilot still does not work correctly, the issue may be calibration, wiring, or a faulty sensor. Consult the maker's manual or a qualified installer, and see our article on calibration importance.

Why does the sensor need to be kept away from magnets?

Magnets can change the magnetic field around the compass, causing incorrect heading readings. This can make the autopilot steer the wrong course. Keep magnetic tools and speakers away from the sensor.

Can I clean the sensor while the autopilot is on?

No. Always turn off power to the autopilot before cleaning any part. This prevents accidental short circuits and ensures you do not disturb the sensor while it is active.

Do I need to recalibrate after cleaning?

Cleaning the outside of the sensor should not change its calibration. However, if you move the sensor or replace it, recalibration is usually required. Follow the maker's instructions or hire a professional.