Canon 24-105 II Autofocus Not Working: IS Repair
When a Canon EF 24-105mm f/4 L IS II won't lock focus, the culprit can be the image stabiliser unit rather than the AF motor. We replace it for a fixed €400.
Symptoms
- Autofocus hunts and won't lock onto the subject
- Images look soft or undefined even when focus confirms
- Problem appeared suddenly, without a drop or knock
- Sharpness doesn't improve at any focal length
Canon 24-105 II autofocus not working, with no drop or knock to explain it? On the EF 24-105mm f/4 L IS II USM the real culprit is not always the focus motor — in the repair we describe here it was the image stabiliser unit. Whatever the cause turns out to be, the diagnosis is free and this repair has a fixed price of €400.
The symptoms
A customer brought us his EF 24-105mm f/4 L IS II that had suddenly stopped locking focus on the subject. The lens had never been dropped and had taken no particular knocks — one day the autofocus simply stopped working properly, and images came out undefined.
That last detail matters: when the picture itself is soft, the lens's AF system has nothing sharp to lock onto, so the symptom presents as "autofocus not working" even when the focus motor is fine.
What causes it
Inside this lens, the image stabiliser is a plastic-housed unit containing a floating lens group, moved by a system of motors under electronic control, which damps the vibrations produced while shooting. When the electronics in this unit fail, the floating group no longer behaves correctly and the image becomes undefined — and with a degraded image, focus can never truly lock. The fault is electronic, invisible from outside, and only shows up when each part of the lens is tested individually.
Can you fix it yourself?
There is little to try at home beyond the basics: clean the lens contacts, try the lens on another body, and toggle the stabiliser switch to see whether the behaviour changes. If the images remain undefined and focus still won't lock, the problem is internal. Diagnosing it requires opening the lens and testing each assembly separately, and replacing the IS unit means a deep disassembly — not a DIY repair.
How we repair it
Before starting the actual repair, our technicians disassembled the 24-105 II and tested every part of the lens to pin down why the autofocus was failing. The conclusion: the problem was electronic, in the stabiliser, which was making the image undefined. The complete IS unit — the plastic component housing the floating lens group with its motors and control electronics — was replaced with a new one.
Once the stabiliser was replaced the lens was back to working like new, we cleaned it internally, ran the final checks, and contacted the customer. More Canon jobs like this one are in our Canon repair department.
Price and turnaround
| Service | Price |
|---|---|
| Image stabiliser unit replacement, Canon 24-105 II | €400 (fixed) |
| Internal cleaning | Included |
| Final test & calibration | Included |
Typical turnaround is 10 working days, which includes the part-by-part diagnosis this fault requires. Return shipping is a flat €20 anywhere in the EU.
Ship your lens from anywhere in the EU — diagnosis is free and the repair is covered by a 6-month warranty. See how it works.
Frequently asked questions
Why is the autofocus on my Canon 24-105 II not working?
Not every focus failure is the AF motor. In the case we repaired, the fault was electronic, inside the image stabiliser unit — its floating lens group made the image undefined, so the lens could never lock focus properly.
How much does it cost to repair the Canon 24-105 II stabiliser?
We replace the complete IS unit for a fixed €400, with internal cleaning and a final test included.
Can the stabiliser really cause focus problems?
Yes. The IS unit holds a floating lens group moved by motors under electronic control; if that electronics fails, the group no longer sits where it should and the image degrades — which looks exactly like an autofocus fault.
Is the Canon EF 24-105mm f/4 L IS II worth repairing?
Usually yes — it is a current, professional L-series zoom, and a fixed-price repair with warranty costs considerably less than replacing the lens.
