Aventon Level.2, Pace, Sinch and Aventure: error 25, motor won't engage or cuts out without braking

You turn your Aventon on and the display shows 25, and the motor won't engage. Or there's no code, but the motor cuts out while you ride without touching the brakes, or keeps pulling when you squeeze a lever. Aventon's manuals for the Level.2, Pace 350 and Pace 500, Sinch and Aventure list 25 as a brake switch fault or brake applied while turning on (Level.2 manual, Pace 350 and 500 manual, Sinch manual, Aventure manual). Short answer: restart without touching the levers. If 25 stays, one lever's motor cut-off sensor is set too sensitive, unplugged or damaged, and Aventon publishes an adjustment guide for it (Aventon brake sensor adjustment).

Most likely cause

Most Aventon models use adjustable Tektro levers with a sensor that cuts motor power when the lever is squeezed. If the sensor is too sensitive, the motor cuts off with no brake applied. If it isn't sensitive enough, the motor keeps running when you brake. If the controller reads the brake as pulled, error 25 shows and the motor won't turn on (Aventon brake sensor adjustment).

Other causes to rule out

• A lever squeezed at power on. The manuals list "brakes applied" as a reason the bike doesn't work (Sinch manual).
• Grit or a loose plug in the brake lever cable (Aventon brake sensor adjustment).
• Bengal, Zoom or Magura brakes. Aventon says these levers have no adjustment, so a 25 on them means the lever should be replaced, or the code doesn't apply (Aventon brake sensor adjustment).
• If 25 stays with both sensors unplugged, Aventon says the wire harness and controller need replacing (Aventon brake sensor adjustment).

How to confirm

1. Turn the bike off, make sure both levers are fully released, and turn it on without touching them.
2. Check both brake lever cables are firmly plugged in at the first connector and free of grit (Aventon brake sensor adjustment).
3. Squeeze and release both levers several times, then restart.
4. As a stationary test only, unplug both sensors. If 25 clears, plug in one side at a time to find the faulty lever. Plug both back in before you ride (Aventon brake sensor adjustment).

Fix options

Restart and clean the plugs (easy)

Clears most one off codes.

Adjust the brake sensor (moderate)

On adjustable Tektro levers, Aventon has you loosen the lever clamp so the lever can rotate, find the sensor adjustment bolt where the cable leaves the lever (not the brake hose bolt), loosen its set screw, then turn the bolt with a 7mm wrench while watching the display. Counterclockwise lowers sensitivity, clockwise raises it. When 25 is gone and pulling the lever still cuts the motor, retighten the set screw without over tightening and test on the road (Aventon brake sensor adjustment). The set screw is a 2mm hex on older levers and a Phillips screw on newer ones.

Replace the brake lever (moderate)

If 25 can't be cleared by adjustment, for example after a crash, Aventon says replace the lever (Aventon brake sensor adjustment).

Replace the harness or controller (pro or Aventon)

Only when 25 stays with both sensors unplugged (Aventon brake sensor adjustment).

Parts

• Brake lever with motor cut-off sensor
• Wire harness or controller (only if the code stays with sensors unplugged)

Videos

When to get a pro

• A lever damaged in a crash, or brakes that feel soft. See e-bike brakes.
• If the motor doesn't cut out when you pull the lever after adjustment.
• Harness or controller replacement. See check brake cut-off and throttle and aventon troubleshooting.

Sources

• Aventon brake sensor adjustment, rideaventon.zendesk.com
• Level.2 manual, cdn.shopify.com
• Pace 350 and 500 manual, cdn.shopify.com
• Sinch manual, cdn.shopify.com
• Aventure manual, cdn.shopify.com
• How to: Adjust the Brakes on the Soltera, youtube.com

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