Which OBD app works best on your phone and Bluetooth scanner will be a matter of trial and error for you. What OBD scanner do I need? OBD readers tested The product is supplied with an in-depth user manual which explains generic diagnostic codes and operation instructions. The product is supplied with an in-depth user manual which explains all the diagnostic codes and operation instructions.

Please note: The reader will not be able to read codes for airbags and braking systems. OBD II readers mainly read OBD II codes (emissions systems) in 99.9% of vehicles. Wireless readers are smaller and generally cheaper, but need a connection to a smartphone or tablet. Wired readers are more convenient, easier to use with gloves and grimy hands, but usually provide less information. We tested both.A technician may describe soft codes as historical anomalies or intermittent codes that don’t affect vehicle function. Most scan tools automatically communicate with the vehicle modules over the communication network. I’ll also assume your tool communicates with the vehicle modules and doesn’t respond with “No Communication” if it does see Scan tool faults below. Compare perhaps with a telephone as a box or device that transfers voice information from one person to another. If the person speaking on the other end of the phone is talking a different language to yours, you still need something extra at your end to interpret that language and present it in a form you can use. Such as a clever brain that can translate that other language into English for example?

ELM327 defines what specific items of information get transmitted. From the tens of thousands of possibilities. The reader requires no battery, it plugs straight into the vehicle’s connection point for it to power up. It is compatible with all petrol vehicles from 1996 and diesel vehicles from 2004 that are OBD II compliant (including CAN). It all depends what app or other software you are using to receive the data and display that data in a meaningful way. Also depends what sort of data (which data items of the tens of thousands possible) it is that you want to read. If you wanted to passively read engine or other systems fault codes for example, you would still need some other software app (and a suitable piece of hardware to run it on), to receive the transmitted data, interpret the fault codes and then display those in some way in a human readable form. “Torque” and “Torque-lite” are a pair of apps that also run on Android smartphones to accept and display a limited number of fault codes, with some interpretation what those mean. There are others.

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A scan tool commonly won’t communicate because one faulty module pulls the whole system down. A damaged circuit is common too, but not as common as a failed module.

Draper has a good reputation for making products that stand the test of time, and we have no reason to doubt this code reader's staying power; at the time of testing it was one of the pricier offerings here, but deserves its Haynes Recommended award. The device will work with all OBD II certified vehicles from 2001 onwards (including CAN). Not compatible with motorcycles and hybrid & electric vehicles. This reader’s large colour display looks like it should be a touchscreen, but it’s not. However, the physical buttons make navigation a cinch. What’s more, the tool gives live vehicle data readings and there’s a “Code Lookup” feature that provides a clear explanation of the diagnostics codes.The tool also runs a number of diagnostic tests such as the O2 sensor test, I/M readiness test and EVAP test. The reader can also determine the malfunction indicator lamp status, review emission readiness status, retrieve VIN (Vehicle Identification Number) on 2002 and newer vehicles that support Mode 9 and more. CAN employ a twisted pair of wires (one wire CAN high typically 3.5-2.5 volts oscillating and the other CAN low typically 2.5 – 1.5 volts oscillating) that loop the vehicle, connecting all the modules on the network. As with its bigger brother, Mode 6 gives you additional system monitoring and you can access information on the emissions control systems.