The check engine light (ECS light on older models) on your Subaru, that is? Well, don’t panic, it may not be all that bad after all. In most cases all it means is that the engine control module (ECM) that controls the vehicle’s engine has detected a problem with a solenoid or sensor or other emission related device. Examples of this could be a faulty canister purge control solenoid, weak catalytic converter, crank angle sensor or engine coolant temperature sensor and even a loose gas cap! When a sensor fails it triggers a response from the ECM that illuminates the check engine light. This event also creates a fault code that corresponds to the faulty sensor or system. (These codes are accessed with a scan tool device and are listed in the Factory Subaru Shop manuals.) The sensors help the vehicle’s computer know the engine’s status so that it can decide how much fuel to deliver, how much to advance or retard the ignition timing, etc. In Subarus after 1987, the code is stored in the ECM’s memory. Even if the light goes back off, your service personnel will be able to pull the code from the memory of the ECM to see what transpired. We can even tell you at what speed you were driving and what the engine temperature was when the problem occurred! In most cases, once the code is accessed, the faulty sensor or solenoid is replaced, memory is cleared and you’re on the road again.

There are some exceptions to this "code" system such as a poor connection between the ECM and the sensor or other unknown. Your newer Subaru’s (1995 up OBDII) also have the ability to give performance codes such as a cylinder misfire or loss of pressure in the fuel tank. In general if your check engine light does illuminate STEADY, it’s a good idea to do a visual under-hood inspection of all fluids and anything that may be obviously loose or disconnected. Make sure the gas cap is fully tightened. If all looks good and the car is still running well, proceed to your service facility at your earliest convenience for a diagnostic scan of the code. In the case of a FLASHING check engine light it is advised that you shut the car off immediately and have the vehicle towed to your repair facility to diagnose the problem. The flashing light is communicating that the problem may be severe enough to damage the catalytic converter or other components on the engine.

Hopefully, now that some of the mystery has been unraveled on the check engine light subject, you’ll be better able make a better decision whether to interrupt your family vacation or just continue happy motoring until it’s convenient to set an appointment to have the code addressed.

Always feel free to call us or email us if you have any questions about your particular vehicle and a check engine light occurrence.