# PAX D135 Troubleshooting

Common error codes and solutions for the PAX D135 card reader.

## Error 4002 — Card Read Failure (EL_TRANS_RET_READ_CARD_FAIL)

This error indicates a general card read failure from the PAX D135.

### Possible causes

- Card not positioned properly over the NFC reader
- Card removed before the read completed
- Weak or damaged card NFC antenna
- Dirty or damaged chip contacts (for chip cards)
- RF/EMI interference from nearby electronics
- Poor Bluetooth connection between the phone and the reader
- Dirty magnetic stripe or reader head (for swipe transactions)


Hold your card steady on the reader for 1–2 seconds until you see confirmation.

## Error 4006 — NFC Interference

Devices with their own NFC reader can cause interference with the D135. It is advised not to directly mount the D135 to the back of a phone.

### Disabling NFC on Android

Certain Android models allow you to disable the phone's NFC via settings:

1. Go to **System Settings**


Android System Settings
1. Tap **Connected Devices**


Connected Devices menu
1. Tap **Connection Preferences**


Connection Preferences menu
1. Tap **NFC** and switch the toggle off


NFC toggle off
## Restarting the Device

If the device is unresponsive, you may need to hold the power button for up to 30 seconds to fully restart it.

## Charging the Device

Charge the battery only with PAX-approved power supplies. Using others may damage the product and void the warranty.

Charging time must not exceed 24 hours. If the battery is empty, recharge it fully, then disconnect the device to avoid shortening its life.