Does the display show any reading - even 0 mph?
If the display is blank check the battery.
Is there a line on the sensor? If so the magnet should align with the line.
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The Lord is merciful and gracious, slow to anger and abounding in steadfast love. - Psalm 103:8
I am a cyclist. I am not the fastest or the fittest. But I will get to where I'm going with a smile on my face.