The string may be far from target
A tuner cannot know which string you intended to play. If the low E string is very loose, it may correctly display D, C, or B. Move slowly while watching the chromatic note sequence.
Overtones can dominate
The pitch detector may briefly identify a fifth or octave when the fundamental is weak. Pluck away from the bridge, reduce distortion, and allow the note to settle.
Check the preset and octave
A 432 Hz preset differs only slightly from standard, but alternate tunings change note targets. Large octave mistakes are more dangerous: never keep tightening a heavy string merely because the note letter appears correct.
Step-by-step check
- Stop and identify the selected tuning.
- Mute all strings except the one being tested.
- If necessary, use a separate chromatic tuner to identify its current note and octave.
- Move slowly toward the target note in the correct octave.
- Replace or reseat the string if its pitch remains unstable.
Reliable tuning habits
Work with one string at a time, use a moderate and repeatable picking attack, and let the initial pitch settle briefly. Make the final adjustment by approaching the target from below so slack is taken out of the tuning post and nut. After all six strings are close, repeat the entire pass because every tension change can slightly affect the other strings.