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Reading A Check Engine Light

Got a pesky engine light that’s been glaring at you for weeks? Read on and you can fix it yourself.

Is it safe to drive your car with the check engine light on?

In most cases, the engine is trying to protect itself from damage, and let you know that it requires inspection. It’s best to find out exactly what it’s trying to tell you before damage occurs, and you end up stuck by the side of the road. A diagnostic scan tool will let you figure this out easily. But what is a diagnostic scan tool, and how do I use one?

What does OBD2 Stand for? OBDII?

OBD stands for On Board Diagnostics, this is an automotive term referring to the vehicles built in self diagnostic & reporting system. OBD2 is a universal port fitted to most vehicles in the last 20 years that gives users access to this system via an OBD2 Scan Tool. This allows users to access vital engine information delivered from the vehicle's sensors and flag with the user via check engine light any abnormalities with the health of the engine.

An OBD2 code scanner plugs into a special socket under your dashboard, fuse panel or centre console, which is fitted to most vehicles from 1996 onwards. If you can't locate the connector make sure you check your owners' manual as it may be in an odd location or have a look online.

Scan tool

What could cause the check engine light to come on?

There are several reasons why a check engine light may illuminate on your instrument cluster. A check engine light is simply a way of the engines' computer telling you that there is a fault with one or more of the sensors or mechanical functions in the vehicle. This is a good time to inspect the reason why and find out what caused the issue. If ignored, this could lead to bad fuel eco, poor performance or worse, an engine failure and additional costly repairs.

In some cases, your vehicle will go into "limp" mode to protect further damage to the engine. The engines performance will be drastically reduced to prevent damage and in some cases will switch off and not allow the user to turn it on until the errors are cleared.

What types of OBD2 Scan Tools are available?

There are three types of OBD2 scan tools available. Plug and play, Bluetooth and a hybrid of the two. Plug and play scan tools do exactly that, they plug into the OBD2 port on your vehicle and have a screen to give basic readings with options to live feed data display. Bluetooth is a dongle that plugs into your OBD2 port and connects to your smartphone. You gain access to the bluetooth scan tool using the manufactuer application to read the data from the dongle.

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Step 1 - Setup the vehicle

Step 1

This is a quick guide to checking your engine light to read and clear codes using an OBD2 Scan Tool. First we need to ensure the car is sercure and flat. Park your car on level ground, switch off the ignition and ensure the car is parked withthe handbrake on and in park if applicable.

Step 2 - Locate the OBD2 port

Step 2

Locate the OBD2 socket under the dash, behind a fuse panel or in the centre console - and plug-in the OBD2 scanner. If you are unable to find your OBD2 port, look in your user manual, service manual or online to find the solution.

Step 3 - Turn on

Step 3

Turn your ignition to the ON position and check to see if your screen turns on. If you have a OBD2 Bluetooth dongle, it should have a light blinking to indicate it's ready to connect via Bluetooth. Connect your phone to the bluetooth dongle as per the instructions of the scan tool as some may differ.

Step 4 - Read codes

Step 4

Follow the instructions on the display and scroll to read codes as per your scan tools instructions. THe scan tool should show you a fault code, you may need to refer to the service manual to find out what it is. Some scan tools have this built in and will note what the code repersents.

Step 5 - Clear codes

Step 4

Now that you have the cause of the check engine light established, some (not all) OBD2 Scan tools can clear the codes to test if it comes up again, or after the repair has been completed to ensure the repair was successful.

Whether a simple code reset cleared the problem, or you’ve got a part that needs replacing, you’re already ahead. Paying a dealer to check and reset these codes can be a costly exercise! Just make sure you keep tabs on your OBDII reader because once your mates find out you own one, they’ll all want to have a go!