Card Machine Not Working? Common Problems and Quick Fixes

There's never a good time for a card machine to stop working, but it always seems to happen on the busiest day. The queue's growing, the customer's waiting and the screen just says "connection error".

Most card machine problems have simple causes and simple fixes. This guide covers the common ones in the order you should try them, plus what to do while you sort it out so you don't lose the sale.

First: keep taking payments

Before you start troubleshooting, get the queue moving.

• Use Tap to Pay on your phone. If your provider supports it, you can take contactless payments on your phone while the main machine is down. Set this up before you need it. Our guide to Tap to Pay on iPhone and Android explains how.
• Send a payment link. Many providers let you text or email a link for the customer to pay on their own phone.
• Use a spare reader. A £19 to £29 spare is cheap insurance.
• Take cash, if you accept it.

Then work through the fixes below.

Quick fixes at a glance

Connection problems

This is the number one cause of "broken" card machines.

If your machine uses WiFi:

1. Check other devices can get online on the same network.
2. Move closer to the router.
3. Restart the router, then the card machine.
4. Check the WiFi password hasn't been changed.
5. If your machine has a SIM, switch to mobile data.

If your machine uses a SIM:

1. Check the signal bars on the screen.
2. Move near a window or outside.
3. Restart the machine.
4. If you're in a known blackspot, try WiFi or your phone's hotspot.

If your reader pairs with your phone:

1. Check your phone has mobile data or WiFi.
2. Check Bluetooth is on.
3. Keep the reader close to the phone.

Bluetooth pairing problems

If your reader won't connect to your phone:

1. Turn Bluetooth off and on again.
2. Close the provider's app completely and reopen it.
3. Restart the reader by holding the power button.
4. Restart your phone.
5. In your phone's Bluetooth settings, "forget" the reader and pair it again through the app.
6. Check the app has permission to use Bluetooth and location, which some phones need for pairing.
7. Update the app.

Declined payments

If one card is declined, the problem is almost always on the customer's side. Their bank might have spotted something unusual, the card might be blocked, or they might be out of funds. You can't override a decline.

What to do:

• Ask them to insert the card and enter their PIN.
• Suggest Apple Pay or Google Pay on their phone.
• Ask for a different card.

If every card is being declined, the problem is more likely your machine or account. Check your connection, then contact your provider. Your account could have been paused for checks, especially if you're new or took an unusually large payment.

Frozen screen or won't switch on

• Frozen: hold the power button until the machine switches off, then switch it back on. Some models need the button held for ten seconds or more.
• Won't switch on: plug it in and leave it for at least 30 minutes. A completely flat battery can take a while to show signs of life.
• Battery dies quickly: batteries wear out. Ask your provider about a replacement if it's under warranty.

Printer problems

• Open the cover and check the paper roll is the right way round. Thermal paper only prints on one side.
• Use the right size and type of roll. Check your manual.
• Clean the print head gently if prints are faint.
• If you're out of paper, offer an email or text receipt.

Software updates

Card machines need updates for security. If an update is waiting, the machine may refuse to take payments until it's done. Connect to reliable WiFi and leave it to finish. Don't switch it off halfway.

To avoid this mid service, let your machine update overnight or before you open.

Error codes

Each provider uses its own codes, so look them up in your provider's help centre. Write down the code and any message before you call support. It speeds things up.

When to call your provider

Get in touch if:

• Every payment is failing even with a good connection.
• The machine is damaged or has been dropped.
• There's a security message or the machine says it's been tampered with.
• You think your account has been paused.
• The battery won't hold a charge.

Have your account details, the machine's serial number and any error codes ready. If you rent your machine, the provider should usually repair or replace it.

How to avoid problems in the first place

• Set up a backup. Tap to Pay on a phone, or a cheap spare reader.
• Test before opening. A quick test payment in the morning catches problems early.
• Keep it charged. Use a dock or charger during the day.
• Check your WiFi coverage. Especially for portable machines in large venues.
• Update regularly. Both the machine and the app.
• Keep spare paper rolls.
• Look after it. Cases help mobile machines survive drops and rain.

If problems keep happening, it might be time for a new machine or provider. Our guide to PDQ machines covers the main types of terminal.

FAQs

Why does my card machine say no connection?

It can't reach the internet. Check your WiFi or mobile signal, restart the router and machine, and try another connection if your machine has one.

Why is my card machine declining all cards?

If it's every card, check your connection first. If that's fine, contact your provider, as your account may have been paused.

How do I reset my card machine?

Hold the power button to restart it. A full factory reset is rarely needed, and you should only do it if your provider tells you to.

Can I still take payments if my card machine is broken?

Yes. Use Tap to Pay on your phone, send a payment link, use a spare reader or take cash.

Why won't my card reader connect to my phone?

Usually Bluetooth. Turn it off and on, restart both devices, check the app's permissions and pair the reader again through the app.

Who pays to fix a broken card machine?

If you rent it, the provider usually repairs or replaces it. If you bought it, check the warranty. SumUp, for example, includes a warranty with its readers.

What should I do if my card machine says it's been tampered with?

Stop using it straight away and call your provider. Don't try to open it or keep taking payments on it. A tamper warning can be triggered by damage or a fault, but it's a security alert, so treat it seriously.