
Check Engine Warning Light
The Check Engine Light
This is a fault-registering system connected to sensors all over the car, engine, fuel and emissions system and is an indication that you may need mechanical repairs or electrical repairs. When the check engine light comes on, it can mean many things. There are something like 4,000 unique OBD2 codes that can be stored. Handheld OBD2 diagnostic tools can be plugged in to the OBD2 port which is normally under the dash on the driver’s side or centre console or engine bay. These tools can read out the fault code and/or reset the system to contain no codes. Codes are split into two categories – historical/inactive, and 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).
P0440 OBD-II code. This is the most common code you’ll find and it’s the first thing you should check. P0440 is the code for Evaporative Emission Control System Malfunction which covers a multitude of sins. The 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. In fact, on a lot of cars, that code is so common they’ll actually have some way of telling you to check the gas cap. In some Honda’s, for example, if a P0440 code is logged, the dash scrolls “CHECK GAS 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 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.



