The check engine light can be referred to by many names such as EML (Engine Management Light) or MIL (Malfunction Indicator Light.) Luckily, as a driver, you don’t need to know the ins and outs of motoring terminology. You simply need to know what to do should the check engine light illuminate in your Audi. In this article, we’ll be taking a closer look at how the light works and the different factors which can cause it to illuminate.
How the Check Engine Light Works
You Audi has an onboard computer which is known as the Powertrain Control Module, or PCM. The job of the PCM is to monitor the signals by various sensors in the engine system. It also tweaks engine and transmission function to help improve performance and achieve better fuel economy.
The PCM is able to test the function of the various systems of your engine. If it notices a fault with any of these which compromises engine function or puts the safety of the vehicle at risk it will turn on the check engine light and store a fault code in its memory. There are hundreds of different codes that the PCM can use to highlight the exact nature of the problem. These codes can be read using a diagnostic reader which allows the individual working on your Audi to identify the problem quickly.
Common Causes of Check Engine Light Illumination
There are many factors that can cause the check engine light to illuminate. In fact, most forms of engine-related part failure may trigger the warning light. However, this doesn’t mean that the light should ever be ignored.
Remember, the check engine light is a signal to the driver of a problem relating to the engine, the most expensive part of your car. While oftentimes this is due to a minor issue, running the risk of serious engine failure simply isn’t worth it. Let’s take a closer look at some of the common reasons that can cause check engine light illumination.
The likelihood of certain types of failure depends upon the age of your Audi, as part failures caused by wear and tear become much more likely. In fact, when your car passes a certain age, you can almost guarantee that check engine light illumination is due to a particular part due for replacement as opposed to parts failing prematurely or becoming faulty.
Oftentimes check engine light illumination can be due to driver error. A loose-fitting gas cap, for example, can allow fuel vapors to leak from the engine system which the PCM can view as a gas leak, leading to warning light illumination. Therefore, when you visit the pumps make sure your gas cap is tightly secured before driving away.
Other basic maintenance factors, such as low engine oil, can also play a part in why the check engine light has illuminated. Make sure your drivers-side floor mat fits correctly and is correctly secured, as a poorly fitting and moveable mat can hamper with your gas and brake pedals, causing the PCM to assume an issue.
Aside from driver error, probably one of the most common and easiest to fix causes of the check engine light are worn out spark plugs. Spark plugs are used inside your engine to pass a spark which ignites the fuel. The spark used is high-voltage and wears away at the tips of the plugs over time. This causes the gap to widen between each set of plugs making transferring a spark much more difficult. This leads to an increased rate of misfires and stalls causing the PCM to detect a problem.
Other parts which may cause the check engine light to illuminate include:
- the O2 sensor
- vacuum leaks
- the MAF sensor
- ignition coils
- leaky purge valve
- leaky vent valve
- the air/fuel ratio sensor
- the EGR valve
- failed catalytic converter
- false error code