The most common cause of sensor connection issues is alignment. The magnets should be aligned with the indicator notches on the sensors, passing within 1/8 inch (4 mm) of the sensor. The indicator line on the cadence sensor is located on the upper portion of the battery cover section while the indicator line on the speed sensor is visible on the speed arm.
For troubleshooting, re-position the magnets and sensors such that the magnets pass over the indicator notch lines, then test in the Wahoo app. If you still have issues, it's sometimes useful remove the sensor from the bike, then manually pass the magnet over the sensor by hand to test for a change in response.
- If the sensor arm is at all loose from the main sensor body, this can cause one sensor to read, but not the other. If you're getting only one reading, try fully tightening the bolt which connects the arm to the main sensor body.
- Be careful when moving or rotating the speed arm as it contains a small wire which connects the speed sensor to the battery. Over-rotating the speed arm can potentially snap this wire, disabling speed readings.