A scoping tool works best for capturing glitches in network systems. But we’ll work with just a DVOM as most will have access to a voltmeter. Industry-recognised diagnostic code reader that is suitable for all kinds of users, including roadside mechanics, garage mechanics and home mechanics.

Your vehicle is stuffed with modules, each one tasked with a particular system to manage. Your ECU (Engine Control Unit) takes care of the engine, your TCM (Transmission Control Module) takes care of the tranny, and your BCM (Body Control Module) takes care of the vehicle accessories. You get the idea. 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. 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.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 An OBD reader has traditionally taken the form of a handheld diagnostic computer that communicates with your car’s brain to diagnose fault codes, among other things. You can pay as little as a tenner for an OBD scanner and as much as hundreds of pounds – with the latter offering a multitude of features – but whichever you choose, they should all have the same minimum requirements, and be able to: The product is supplied with an in-depth user manual which explains generic diagnostic codes and operation instructions. 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. The tool also runs a number of diagnostic tests such as the O2 sensor test, I/M readiness test and EVAP test.

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). As a "starter for 10" therefore, I would say it scores 20! Not least as it doesn't break the bank! (OMG - I'm sounding like a Yorkshireman?) It has all of the features of the other offerings in this test and displays monitor and I/M readiness status (which provide insight into the car’s emission control systems), O2 sensor info and evap system tests capabilities (mostly concerns US models with a charcoal canister to trap and store fuel vapours).We plugged the readers into a selection of cars of different ages, including a 2008 Mazda 2 and 2014 Peugeot 208 with known faults that were generating a warning light. Wireless readers were connected via Bluetooth to an iPhone using the app suggested by the device’s instructions. Verdict It also has permanent code retrieval, on-board monitor test (Mode 6, for additional component/system monitoring), reads fault code pending data, DTC code lookup function and lets you reset the oil change indicator. 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. As with its bigger brother, Mode 6 gives you additional system monitoring and you can access information on the emissions control systems. While total communication loss is rare, it’s more usual for one module to go down, and the other working modules report its loss by setting a fault code.