Resolving Connection Issues

The Piston application requires an ELM327 based device, either Bluetooth or WiFi, to work.

The latest versions of the application, after failing to connect, show a message with information on how to solve your particular problem as it knows the context (i.e. what exactly failed).

Bluetooth Devices

  • Please make sure you have selected the correct device in the application Settings.
  • If you can’t establish a Bluetooth connection you may try to unpair your ELM327 device in your phone settings and pair it again.

WiFi Devices

  • Please make sure you have entered the correct WiFi address and port (the default values work for most devices, but not for all) in the app settings.
  • If you can’t make a WiFi connection, please make sure you are connected to the WiFi network of your OBD2 device.
  • Try to turn off the Mobile Internet (3G/4G/5G). This is the most common reason for WiFi connection failures.

OBD2 Connection Problems

It may happen that your phone will connect to the ELM device, however the ELM chip is unable to connect to your vehicle’s ECU. The indication of the OBD2 connection issue is the UNABLE TO CONNECT response shown in the Communication screen of the app with other commands executed without problem e.g. AT Z.

  • The ignition is off. This is the most common problem. You need to turn on the engine ignition in order to activate the ECU. You may as well start the vehicle’s engine.
  • The UNABLE TO CONNECT response may also mean that the ELM327 device cannot detect the OBD protocol. You may try to select the OBD protocol in the app settings (probably you will need to Google which one your vehicle uses). Many dongles have issues connecting to the vehicles using the J1850 PWM protocol. This is the protocol used by Ford in many of their vehicles up to mid 2000’s.
  • You may try to select the Wait longer for ECU responses option in the Settings - it helps to establish connections with some ECUs.
  • The ELM devices differ in quality and firmware. It sometimes happens that the ELM327 chip may stop responding. In this situation you may unplug your ELM device and plug it again.

Premium Version

Payment options

The Premium version is an in-app purchase and we are required to use Google Play’s billing system as described here . What this means for us we are only able to provide the payment options supported by Google. Alternative methods like Blik for example are not available at the moment.

The payment is handled by Google and we don’t have access to your personal details like the card number.

Restoring Premium Version

This application checks with the Play Store at every start if you have the Premium in-app purchase active. It may happen, especially after activating a new Android device, that the Play Store hasn’t downloaded all in-app purchases yet. If the application doesn’t see the Premium upgrade you may try the following steps:

  • Navigate to the Play Store Application and make sure you are logged-in with the same account you used to purchase the Premium upgrade.
  • Navigate to the Play Store Application and under your account section go to the Payments and subscriptions menu and then Budget and history. This process usually triggers the Play Store to download all the in-app purchases. You will also be able to check if the Premium upgrade is visible in your account.
  • If in the Play Store Application you are logged-in using a different account than the one used to purchase the Premium version, please:
    1. Uninstall the Piston App
    2. Switch the user in the Play Store Application to the one used to purchase the Premium version
    3. Restart your phone
    4. Install the Piston App again.
  • Restart your phone and make sure you are connected to the Internet.
  • Tap on the Upgrade to Premium button, but DO NOT proceed with the payment.
  • If none of the above helps please send us a message at with your order id - you can search your emails for the GPA text, all order numbers start with it.