When the check engine light illuminates it can be a source of great stress for the vehicle owner. For those not confident in their knowledge of vehicle maintenance, it seems like many different reasons could cause the light coming on. A trained VW service technician should be consulted to pinpoint the exact source which is causing the light to illuminate.

Because of the complexity of today’s engines, there can be many possible causes for a check engine light to illuminate. Some common reasons are:

Failed Oxygen Sensor

Oxygen sensors are a very common sensor to fail in vehicles. It tells the car how much air and fuel to mix for the engine to run smoothly. Failed oxygen sensors can come on as the result of vacuum leaks, but a skilled VW service technician will be able to verify if this is the cause. 

Failed Catalytic Converter

A car’s catalytic converter is responsible for turning toxic combustion gases from the motor into predominantly harmless exhaust. Many modern cars can have two or more catalytic converters.  One sign of a failed catalytic converter can be an unpleasant odor.

Bad Ignition, Spark Plugs

This is frequently the cause of a failed catalytic converter as the ignition system provides the spark necessary to ignite the fuel in the engine’s cylinders. When the fuel is not sufficiently ignited, it passes through the exhaust system into the catalytic converter. Common signs include a car starting and then dying, not starting at all, or hesitating when accelerating.

Mass Air Flow Sensor Failure

This sensor measures the amount of air passing through the intake, then helps the car’s computer determine the optimum mix of fuel and air to make the car run smoothly.

Worn Gas Cap

Air allowed into your car’s fuel system from a worn or loose gas cap allows evaporative emission vapors to leak out.  This triggers a response from the monitor and causes the engine light to come on. The seal around the cap can weaken over time, requiring it to be replaced. An original equipment cap is recommended for the best results.

At Ottohaus, we provide comprehensive VW service. If your check engine light comes on contact us immediately. We’ll diagnose the problem and let you know what the solution is. Our trained technicians will then be able to get you safely back on the road.