Treadmill Maintenance Guide | Tips & How to Fix E1, E2, E3, AC/DC-4 Error Codes

E1, E2, E3: Common Treadmill Errors & How to Fix Them

Take a photo of the error code, as support will ask for it, and it saves describing the fault from memory.

Communication Faults (E1)

Communication faults, often flagged as E1 but numbered differently across brands, show up when the console and the control board stop talking to each other. The telltale symptom is a console that lights up and accepts input while nothing downstream responds. 

The most common physical cause is a loose, pinched, or damaged data cable running between the two components. Inspect the cable length for pinch points, fraying, or visible damage. Replace the cable if it's damaged; replace the control board if the error persists after you've confirmed the cable is good.

Drive Motor & Control Board Faults (E2)

This second family of codes points to the drive system, either the motor itself or the board commanding it. 

Symptoms include a belt that hesitates under load, stops shortly after starting, or never moves despite the console reading a speed. This is one of the more serious categories because the fault can sit on either side of the motor-to-board connection.

First, verify whether the motor operates correctly. If it is working, inspect the control board for defects.

Speed Sensor Faults (E3)

Speed sensor faults trace back to a small magnetic sensor that reads a magnet mounted on the front roller to track belt speed in real time. When the sensor loses that signal, the console cannot confirm the belt is moving at the commanded speed. 

The fix is usually mechanical. Inspect the sensor's position relative to the magnet, reseat any connectors, and replace the sensor if the gap or alignment is off.

On treadmills with powered incline, a similar code can instead relate to the incline motor or elevation system. The machine commanded an incline change, did not detect the movement, or the elevation stalled mid-adjustment.

Because incline faults and belt faults can look similar on the console, rule out belt lubrication and tension before assuming the incline motor has failed.

What Does the AC/DC-4 Error Code Mean?

The AC/DC-4 error is a high-current fault. The motor is pulling more amperage than the control board considers safe, and the system shuts down to protect itself. This is the code most directly tied to deferred maintenance. 

Belt friction, an over-tightened belt, a worn deck surface, or degraded motor components all force the motor to work harder, pulling more current. The classic giveaway is a treadmill that runs fine with no one on it but shuts off the moment a person steps on and adds load.

Because the AC/DC-4 is a load-triggered fault, the diagnostic path is straightforward: eliminate friction first, then evaluate the motor. Running the belt at low speed with no user and observing whether the code appears tells you immediately whether the issue is load-dependent. If it only triggers under body weight, lubrication and belt tension are the right starting points. If it triggers even at idle, motor wear or a failing control board is the more likely cause.

Treadmill Maintenance That Prevents Error Codes

Lubrication

Lubrication is the single highest-impact maintenance task you can perform on a treadmill, and using the wrong product is one of the most common and costly mistakes owners make. Use only the silicone lubricant your manufacturer approves. Never use WD-40, household oils, or any petroleum-based product.

SOLE ships a tube with every treadmill, so most owners already have what they need for the first application.

Belt Tension

A belt that is too loose slips under load and can trigger speed sensor errors, while one that is too tight puts constant strain on the motor and rear roller bearings.

Tighten the rear roller only enough to stop the belt slipping at the front roller, then walk on the belt and confirm it does not slip or hesitate with each step. Adjust by turning the rear roller adjustment bolts evenly, a quarter turn at a time.

Cleaning Routines

Dust and debris accumulate inside the motor compartment faster than most owners realize, and that buildup acts as an insulating layer that causes motors to run hotter than designed. Heat is a primary cause of premature motor failure. 

Vacuum around and beneath the treadmill weekly, and remove the motor cover every other month to carefully vacuum out the dust and hair that collects there. Ensure the power cord is unplugged first. Wipe down the belt surface and side rails after each use to prevent debris from working its way under the belt.

Dust settles on the floor first, then gets pulled into the motor compartment, which is why the area under the deck needs frequent clearing.

When Should You Call a Treadmill Technician?

Some treadmill faults are safe to troubleshoot at home. Others are not, and pushing past the point of DIY competence raises the risk of injury and can turn a repairable machine into a write-off. Stop troubleshooting yourself and contact a qualified technician if you encounter any of the following:

• The treadmill surges, stalls, or accelerates unexpectedly during use

• You smell burning from the motor area or the electronics bay

• The circuit breaker trips repeatedly when the treadmill is in use

• Error codes return immediately after every power cycle and basic reset

• The belt speed is erratic or unpredictable while a user is on the machine

• The incline moves on its own or will not hold a set position under load

• You hear grinding, loud buzzing, or a high-pitched whine from the motor area

SOLE Treadmills Are Built to Need Less Maintenance

Every treadmill will eventually need attention, but component quality determines how often that happens and how straightforward the fix is when it does. Machines built with higher-grade motors, reinforced decks, and clear diagnostic systems give owners more time running and less time troubleshooting.

At SOLE Fitness, we build our treadmills with heavy-duty motors, reversible decks on select models, and a documented error-code system so owners can act on what they see. Every motorized treadmill we make comes with a lifetime frame and motor warranty and a 30-day satisfaction guarantee. Browse our full treadmill lineup to find the model that matches your setup.

Frequently Asked Questions (FAQs) 

Can I use my treadmill while an error code is displayed?

It depends on the code, but in most cases, the answer is no. Error codes exist to protect both the user and the machine, and running through a fault can cause injury or permanent component damage. Power the machine off, identify the code, and resolve the underlying issue before resuming use.

How do I know if my treadmill belt needs lubrication?

The clearest signs are a belt that feels sticky or sluggish at low speeds, a motor that sounds louder than usual under normal load, or error codes like E2 and AC/DC-4 appearing during use. You can also do a simple friction check: slide your hand under the belt at the center of the deck; if the underside feels dry or rough rather than slightly slick, it is time to lubricate.

Can I fix a treadmill error code myself, or will that void my SOLE warranty?

Routine maintenance: lubrication, belt tension, cleaning, and reseating a loose cable are normal owner upkeep. Anything that involves replacing internal components or opening the machine to test electronics should go through SOLE support first, for safety and to ensure any repair is covered under your warranty. Check your warranty terms on the official SOLE website to see what's covered for your model. 

How often should I service my treadmill to prevent error codes?

If using SOLE, lubricate the deck every 90 hours of use, or sooner if it feels dry, then reset the console's Lube reminder. Reach under the belt every other month to confirm lubricant is still present, vacuum around and under the unit weekly, vacuum under the motor cover and check the wiring every other month, and inspect belt tracking monthly.

What makes SOLE treadmills different from other brands?

SOLE Fitness builds its machines with components originally engineered for hotel use, where treadmills run all day, and backs them with a lifetime frame and motor warranty. The SOLE+ app and its 3,000+ guided workouts are free with compatible SOLE equipment, with no subscription required. The brand has built cardio equipment for more than 25 years, and every machine carries a 30-day satisfaction guarantee.

*Disclaimer: Products and prices mentioned in this article are accurate as of the date of publication and are subject to change. Please visit the official SOLE website for the most current information.