Check Engine Light
Check Engine Light and Maintenance
Modern cars now come with “OBD-II” (On Board Diagnostics 2). This great advancement in technology is a fault-registering system that is connected to sensors all over the car, engine, fuel and emissions system.
When the check engine light comes on, it can mean many things and to continue driving can cause car engine problems.
To date there are thousands of unique OBD2 codes that can be stored. Handheld OBD2 diagnostic tools can be plugged in to the OBD2 port which is commonly under the dash on the driver’s side or centre console or engine bay. Such tools have the ability to read out the fault code and/or reset the system to contain no codes. There are two main categories that these codes fall into: a. historical/inactive, and b. active. The historical codes are lists of things that have been detected in the past but are no longer an issue, whilst the active codes are things that are a problem right now. Codes are subdivided into B-codes (body), C-codes (chassis) and P-codes (powertrain).
The Most Common Fault Code: P0440 OBD-II code.
This is the most common code you’ll find. It is the first thing you should check. P0440 is the code for Evaporative Emission Control System Malfunction which covers a multitude of potential faults. One thing it covers that you can check is your petrol cap (gas cap). Most new cars have a pressurised fuel system and vapour recovery loop. If you’ve filled up with petrol and not twisted the petrol cap until it clicks, you’ve not sealed the fuel system. It won’t pressurise and the OBD2 system will log a P0440 code.
This fault is so common, on a lot of cars the car will have some way of telling you to check the petrol cap. In some Honda’s, for example, if a P0440 code is logged, the dash scrolls “CHECK PETROL CAP” across the odometer display. So if you get a check engine light, check the petrol cap first and see if the light goes off.
Note: Even if the light does go off, the code will likely still be stored in the OBD system and will show up next at your next car service or the next time it is checked. If it isn’t the petrol cap then you’ll need to call for a technician to attend and diagnose the source of the code.
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