Proximity sensor won't detect the actual target
The proximity sensor switches fine on a screwdriver or your hand close up, but won't reliably detect the real target on the machine — it misses, or only sometimes triggers.
Safety first
Setting sensors usually means working near moving machinery. Isolate/secure movement before adjusting brackets, and keep clear of the operating zone when you test under power.
Isolate, lock out / tag out, and prove dead before working unless a live test is specifically required, authorised, and carried out under proper supervision. Always follow local regulations, your site procedures, and the equipment manufacturer's documentation.
Apprentice mode
Full walk-through — the why, what readings mean, mistakes & safety.
Likely causes
Ranked from most to least likely.
- 1
Sensing gap too large for the sensor's range
Most likelyThe real target sits beyond the sensor's rated sensing distance, so it only triggers when something passes closer than the actual target does.
- 2
Wrong sensor type for the target material
#2An inductive sensor's range drops a lot on non-ferrous metals (aluminium, brass) versus steel. A target it can't 'see' well at distance is the classic miss. Capacitive/other types suit different materials.
- 3
Misaligned or drifted bracket
#3A bracket knocked or vibrated out of position moves the sensing face off the target path so it misses intermittently.
- 4
Target too small or moving too fast
Least likelyA small target or high speed gives the sensor too little time/area to switch reliably.
Reports are saved on this device to reflect what you actually find.
Testing sequence
Work through one test at a time. Expected reading and what each result means.
On the tools? Job Mode shows one test at a time with thumb-sized buttons — your place and readings carry straight over.
Enter Job ModeMeasure the actual gap between the sensor face and the real target, and compare to the sensor's rated sensing distance (allow for the reduction on the target material).
Actual gap comfortably within the rated (material-adjusted) sensing distance.
Gap is within range — check alignment and target size/speed.
The target sits beyond the usable range — reduce the gap, or fit a longer-range/correct sensor.
View all expected readings at once
Fault-finding flowchart
The same logic as a decision tree.
- 1start
Prox won't detect the real target
→ step 2 - 2decision
Is the actual gap within the (material-adjusted) sensing range?
Yes→ step 3No→ step 4 - 3decision
Is the sensor type matched to the target material?
Yes→ step 5No→ step 6 - 4result
Target beyond range — reduce gap or fit a longer-range/correct sensor.
- 5decision
Does the LED switch cleanly as the real target passes?
Yes→ step 7No→ step 8 - 6result
Wrong sensor type for the material — fit the correct type.
- 7result
Detection reliable — secure the bracket and confirm over several cycles.
- 8result
Misalignment or small/fast target — realign or reconsider sensor choice/position.
Common mistakes apprentices make
- Proving the sensor on a hand/screwdriver and assuming it'll see the real target the same way.
- Ignoring that inductive range drops sharply on aluminium/brass.
- Setting the gap at the limit of range with no margin for vibration.
- Not securing the bracket after adjusting, so it drifts again.
When to stop & escalate
If no sensor of the right type fits the available gap/position, escalate to review the mounting or detection method rather than running it on the edge of range. Flag if the sensor feeds a safety or critical-position function.
If you're past your competence, authorisation, or the safe limits of the job — stop and hand it on. There's no fault worth getting hurt over.
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Related faults
Proximity sensor triggering at the wrong distance
A proximity sensor detects, but at the wrong point — too early, too late, or inconsistently — so positioning or counting is off even though the sensor 'works'.
Photoelectric sensor not detecting
A photo-eye (through-beam, retro-reflective, or diffuse) isn't detecting reliably — it misses the target, or the output doesn't change when something blocks/enters the beam.
Limit switch or proximity sensor not being detected
A limit switch or proximity/photo sensor isn't registering — the machine doesn't stop at position, the input never makes, or the sensor LED looks wrong for the target's position.