CCTV troubleshooting: a field guide to common faults

Fast fault-finding is one of the most valuable skills in this trade. A good technician does not try things at random. They narrow the problem down, change one thing at a time and write down what they find.

This guide gives you a process, and then the common faults you will meet. Always follow safe working practices, and bring in a qualified electrician where mains power is involved.

A method that works for any fault

1. Understand the symptom. Ask what changed, when it began and whether it affects one camera or many.
2. Check the scope. One camera points to the camera, cable or port. All cameras point to something shared, such as the recorder, switch or power.
3. Start with the simple things. Is it powered? Is the link up? Did someone unplug something?
4. Swap with known-good parts. A known-good camera, port and patch lead isolate the fault quickly.
5. Change one thing at a time. Otherwise, you won't know what fixed it.
6. Confirm the fix. Check the picture, recording and playback before you leave.
7. Record the cause. Write down what you found on the service call, so that the next visit starts with useful history.

Before touching a system, note current settings or back up the configuration where possible. A factory reset should be your last resort, as it can wipe out useful settings.

Camera shows "offline" or no video

This is the most common call. Split the problem into power, cable and network.

Check power

• For PoE, check the switch's port light and power reading.
• Use a tester at the camera end if you can reach it.
• For a 12 V camera, measure the voltage at the camera under load, not just at the adaptor.
• Check that the switch hasn't reached its total PoE limit.

Check the cable

• Test the cable from end to end, including patch leads.
• Look closely at outdoor connectors, as water ingress is a classic cause.
• Look for damage from rodents, other trades or sharp edges.
• Check whether the run approaches the 100 metre limit or uses copper-clad aluminium cable.

Check the network

• Does the camera appear in the discovery tool?
• Has its IP address changed or conflicted with another device?
• Does it respond to ping?
• If using a VLAN, is the switch port configured correctly?
• Were the recorder's credentials changed? An "authentication failed" message may look like offline status on some systems.

Isolate with a swap

Connect a known-good camera on the same cable. If that works, the original camera is likely the problem. If it doesn't, connect the suspect camera near the switch using a short patch lead. If it works there, the problem is your cable run.

Camera keeps rebooting or dropping

Intermittent faults take the most patience.

• Rebooting at night usually suggests a power issue. Infrared raises power consumption, which a marginal cable or switch may not support.
• Dropping in hot or wet weather may mean an overheating switch, an enclosure problem, or moisture in a connector.
• Dropping at certain times could be related to power quality on site, such as heavy machinery starting.
• Dropping when many users view may point to network capacity limits.

Check the camera and switch logs, if available. Look for link flaps, errors or power events on the port. A managed switch makes this far easier.

Picture is blurry

• Clean the lens or dome. Spider webs and dust are common culprits.
• Remove any protective film still on the dome.
• Check the focus, and refocus at the right distance. Use the camera's autofocus or a local monitor, not a compressed phone view.
• Check for moisture inside the housing.
• Look at the bitrate. Too low a setting can make movement smear even with sharp focus.

Picture is too dark or too bright

Too dark

• Check whether there is enough light at the scene.
• Check the exposure settings, including shutter speed. A short shutter gives less blur but needs more light.
• See whether the IR is on and has enough range.

Washed out or silhouettes

• Enable or adjust wide dynamic range.
• Check for backlight, such as a sunny window behind the subject.
• Move or angle the camera so that it does not point directly at the sun, doorway or bright window.

Night vision problems

Lines, flicker or colour problems

• Flicker under lights: Adjust shutter settings to suit mains frequency, usually 50 Hz or 60 Hz, or use the camera's anti-flicker option.
• Rolling lines on analog systems: Suspect a ground loop, poor connector or interference. Check grounding and the routing near power cables.
• Wrong colours: Check white balance. Unusual lighting can confuse automatic settings.
• Pixelated picture during movement: Bitrate is too low, or the network is short on capacity.

Recorder isn't recording

Live view proves nothing about recording. Check:

• Is the recording schedule set on each camera?
• Is the drive detected and healthy?
• Is overwrite enabled? If it is off, recording stops when the drive fills up.
• Has the system run out of bandwidth? Each recorder has an incoming limit.
• Do events trigger recording correctly, if you use motion recording?
• Does the time on the recorder match real time?

Always play back from the camera in question and confirm that the footage is present.

Shorter retention than expected

If a system meant to hold 30 days now keeps only 12:

• Check bitrate for each camera. A camera could have moved from a quiet scene to a busy one.
• Check for new cameras added to the system.
• Look for a camera with a very noisy picture at night.
• Check drive status, as a failed disk reduces capacity.
• Recalculate using our guide to CCTV storage.

Hard drive errors

• Check the status in the recorder's disk page and any health data it shows.
• Look for "abnormal" or "uninitialised" status.
• Reseat the data and power cables with the system switched off.
• Listen for clicking from the drive, and check the temperature inside the enclosure.
• Replace a suspect drive, and warn the customer that recordings on the failed drive may be lost.

If recovery of the footage is important, stop, and do not format anything. Tell the customer before going further, because formatting will erase data.

Remote viewing not working

Start by asking what has changed. Router replacements and app updates are common triggers.

• Does it work on the local network? If it does, focus on the internet side.
• Is the recorder online, as shown in the manufacturer's cloud status?
• Check the recorder's gateway and DNS settings. Wrong values prevent it from reaching the internet.
• Has the phone app or recorder firmware been updated recently?
• Is the site's upload speed sufficient? Try using a lower-bandwidth sub stream.
• Has the router or ISP changed recently? If port forwarding was used, it may be gone. This is also a good time to move to a safer remote access method.

Avoid exposing a recorder's web page directly to the internet. Use the manufacturer's secure service or a VPN. Our guide on cyber security for CCTV installers gives more detail.

Forgotten passwords

Customers often call about this. Be careful, because a password reset request may come from someone who is not authorised to get access.

• Verify the person's authority before helping.
• Use the manufacturer's official reset process.
• Avoid unofficial backdoor tools, which are risky and possibly illegal.
• After resetting it, create proper user accounts, and record who holds the admin credentials.

After a storm or power cut

• Check the recorder first: is it on and does it have the correct time?
• Check the UPS and whether it has failed.
• See which cameras are offline, and whether they share a switch or cable route.
• Test any outdoor runs for surge damage.
• Consider adding surge protection, better grounding or fibre links.

Time and date errors

Wrong timestamps can undermine footage as evidence.

• Check the system's NTP setting and whether it can reach a time server.
• Check the time zone and any daylight saving settings.
• Replace the recorder's clock battery if time resets after every power cut.

When to replace instead of repair

Repairing is not always the right choice. Consider replacing if:

• the equipment is out of warranty and costs more to fix than to replace
• firmware is no longer supported, which raises security concerns
• parts are no longer available
• the same fault keeps coming back
• the equipment is no longer legally suitable for the customer's needs

Explain your reasoning in writing, including what might happen if the customer chooses not to replace it.

Before you leave site

• The original fault has been fixed and confirmed
• All other cameras still work
• Recording and playback have been checked
• Settings changes have been noted
• Any old parts and test devices have been removed
• The customer has been told what happened and what to watch for
• The service record has been updated, with cause, fix, parts and time

Build your own knowledge base

The best troubleshooting resource is your own history. If you record the cause and fix of each call, patterns start to appear: a certain camera model failing, a connector method letting water in, or a particular site with unstable power. Share those lessons at your team meetings. Over time, your team will solve faults faster, and you will design many of them out of future jobs altogether.