How to understand your car’s mind?

Your own car’s mind is tiny and created for readability, so you shouldn’t be amazed how simple it really is to see exactly what its thinking. OBD II is actual version 2.0 of the regular for communicating this information.

The actual data tracked by the OBD II system has been originally designed to keep track of the engine’s emissions and locate issues that caused cars in order to pollute more than regular. Nowadays, producers have extended the standard to contain a lot of data about overall performance and problems.


The OBD II port enables your vehicle to report 3 forms of information: Diagnostic Trouble Codes (DTCs), Real-time data, plus Freeze frame information.

The OBD II Objective

DTCs are just error codes which can be appeared up to determine what issue your vehicle is going through. For instance, the DTC P0302 indicates “cylinder 2 misfire detected”.

Real-time data may be the raw sensor information documented to the OBD computer. This data are a good idea for troubleshooting issues and monitoring engine performance.

Freeze frame data is really a snapshot of the real-time sensor feeds at the right time of a DTC condition. An auto mechanic may use this data to determine that which was going on at that time your car’s check engine” light went on.

The Standard


Within the OBD II standard, there are many protocols for transferring data from the automobile to a diagnostic device.

Name Speed range Used by
ISO: 9141 10 Kbits/sec most Asian plus European producers
J1850 PWM
(Pulse Width Modulation)
100 Kbits/sec Mazda, Ford
J1850 VPW
(changeable Pulse Width)
100 Kbits/sec primarily GM
(Controller Area Network)
varies by application; observe the Kvaser CAN page for more details newer vehicles


The physical connector of the OBD II port is called the information Link Connector (DLC). This is a 16-pin plug that’s generally situated under the dashboard close to the tire. On the Mazda, the connector is situated near the hood release in a difficult-to-photograph placement.

The physical connector of the OBD II port

When looking for your DLC, keep in mind that a three- feet sphere round the car owner is fairly big, and the port could possibly be about the particular passenger’s side. Luckily, there exists a database of DLC areas.

Among the hooks on the OBD II connector is energy from the car’s electric battery, meaning that OBD II visitors don’t need electric batteries or an exterior power source.


A standard group of DTCs can be acquired on almost all automobiles, but every producer includes a huge selection of proprietary codes that will assist pinpoint failures on a particular automobile.

Real-time information delivered through the OBD slot includes vehicle speed, RPMs, air flow heat, and the readings of varied sensors (usually oxygen sensors plus knock-detectors). Don’t assume all automobile passes exactly the same info on the interface, which means that your data streams might vary.


OBD II hardware reduces into two groups: stand-alone devices which are meant specifically for analysis (observe instance at correct), and signal transformation equipment offering the physical connection, but require software on some type of computer or PDA to show the data.

The conversion tools will undoubtedly be slightly cheaper, because they are just interfacing to the automobile and have simply no processor or memory. They may also more versatile, because the software could be modified or replaced.


Just as you’ve got a number of options about the hardware side, you have choices with regard to software also. Don’t assume all OBD program works together with each obtainable converter; however the vendors are very good about offering suitability information, so it is simple to make certain you’re obtaining items that may interact.

OBD II hardware

Since Scan Tool may be the hardware we’re discussing, we will also discuss their software primarily, but there are a handful of other interesting products to say first.

Scan tool

Scantool’s software signifies a new compromise among flashiness, openness, plus functionality. Versions are for sale to DOS, Home windows, plus Linux. The GPL’d C source code can be available for download.

Scan tool polls all the data channels inside a loop, therefore switching off channels you are not interested in will ensure you getting an increased sampling rate about the channels that you will be interested in. You can view the data change instantly, yet because it doesn’t sign or graph the data, it could be hard to note patterns.


It’s worth mentioning a couple of customer devices that use OBD data to supply useful data to drivers. Scan Gauge reads plus clears DTCs, provides a digital dashboard, and has a trip computer. Car Chip is a data logger that tells parents plus bosses in case their cars have been driven harder or farther than they should have been. Thus you can understand your car’s mind.

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