2011 Subaru Forester Has A Check Engine Light

Troubleshooting the Check Engine Light in Your 2011 Subaru Forester: Common Causes and Solutions

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Reviewed by
Andrew Hajjar
Written by RepairPal Car Genius
Updated January 14, 2025
0%
40% chance it's the
Emissions System
0%
60% chance it's
Something else
The most common reasons a 2011 Subaru Forester has a check engine light are an emissions system component, a sensor, or a catalytic converter.
  • Emissions System: A faulty emissions system component, such as an oxygen sensor or EGR valve, can lead to increased emissions and trigger the check engine light.
Proper diagnosis will determine the exact cause of your symptom, saving you money on unnecessary repairs. The diagnostic experts at RepairPal Certified shops have the right tools and experience to solve any symptom.

How much does it cost to fix a 2011 Subaru Forester has a check engine light?

Common Repairs

The total repair cost will vary based on the condition of your vehicle and the number of repairs needed to fix your symptom. Proper diagnosis will save you money by finding the exact repairs needed to fix your car right the first time.

Any time there is an emissions fault the check engine light will be displayed. The purpose of the check engine light is to inform the driver that an emission related fault has been found, and that there are on-board diagnostic (OBD) trouble codes stored in the powertrain or engine control module. Additionally, since the emissions systems are so intertwined into engine control and transmission control systems, symptoms may include nearly any sort of drivability concerns. This may include harsh shifting, failure to shift, hesitation on acceleration, jerking, engine failure to start or run, loss of power, or any number of other drivability issues.

Due to the nature of electrical systems on modern vehicles, the range of problems these can cause are nearly limitless. However, there is a way to categorize them in two ways. Permanent and intermittent problems. Permanent problems appear and remain. This may be the vehicle will not start, the radio does not work, or the door chime will not turn off among many, many others. These problems are more straight-forward to diagnose since they present themselves at all time. This means there will always be a fault to find. Intermittent electrical problems, however, can be difficult or impossible to locate, since they appear then disappear without warning. The best case scenario for an intermittent issue is when replicating the problem is easily accomplished and understood. This allows a technician to make an issue semi-permanent, allowing them to find the fault. Other issues that come and go without warning and cannot be replicated on demand must occur when the technician is servicing the vehicle, otherwise there is no problem to correct. It is most important to understand that electrical system faults always require inspection, and can include the vehicle working in any manner, or not working at all.

Like we noted in the last section, general diagnosis symptoms are the most vague of the bunch. There are several diagnostic spectrums, electrical diagnosis, drivability diagnostics, engine diagnostics, transmission diagnostics, and the list could continue for about 5 or 10 more spectrums of diagnostics. The most important take-away here, is that general diagnostics are diagnostics that have no other spectrum in which they fit, or the problem is unknown. This means that any vehicle left outside of a repair facility with the keys and an authorization to perform diagnosis will be diagnosed under the general diagnosis spectrum.

When the Check Engine Light comes on, you may experience engine performance issues such as poor acceleration, rough idling, or an engine that won't start. In some cases, no abnormal symptoms will be experienced. Other systems like the transmission or ABS can cause the Check Engine Light to illuminate and lights for those systems can come on at the same time. Similar lights may say "Check Engine Soon", "Malfunction Indicator Light" or just "Check". In rare case the engine can overheat.

What are the first steps to diagnose the check engine light on a 2011 Subaru Forester?

When diagnosing the check engine light on a 2011 Subaru Forester, it's essential to adopt a systematic approach that begins with the simplest solutions before progressing to more complex diagnostics. Start by checking the gas cap, as a loose or improperly fitted cap is a common culprit for triggering the light. If the cap is secure, the next step is to read the trouble codes using an OBD-II scanner, which can provide specific insights into the underlying issues. Pay attention to any additional indicator lights that may be illuminated, as they can offer clues about related problems. Inspect the battery and its connections for corrosion, as this can also lead to the check engine light activating. If the light appears intermittently, observe any changes in vehicle performance to help pinpoint the issue. Finally, consult your vehicle's manual and online resources for model-specific problems, and if necessary, seek professional diagnosis for more complex issues. By following this structured diagnostic approach, you can effectively identify and address the cause of the check engine light in your Subaru Forester.

What are the common problems that could cause the check engine light to illuminate in a 2011 Subaru Forester?

When the check engine light illuminates in a 2011 Subaru Forester, it can signal a variety of common problems that DIYers can investigate. One of the first things to check is the gas cap; a loose or damaged cap can lead to fuel vapor leaks, triggering the light. If the gas cap is secure, consider examining the fuel injection system, as misfires or worn spark plugs can also cause the light to activate. Additionally, issues with the oxygen sensor or mass airflow sensor can disrupt the air-fuel mixture, prompting the check engine light to turn on. For those with higher mileage vehicles, a failing catalytic converter may be a concern, as it can become clogged over time. Electrical problems, such as corrosion on battery terminals, can also lead to the light illuminating alongside other warning indicators. Furthermore, faults in the EVAP system, low oil pressure, or even serious engine component failures like head gasket issues may be at play. To effectively diagnose the problem, using an OBD-II scanner to read trouble codes is highly recommended, as it can provide specific insights into the underlying issue.

How urgent is it to address the check engine light in a 2011 Subaru Forester?

When it comes to the check engine light in your 2011 Subaru Forester, understanding the urgency of the situation is crucial for both safety and vehicle longevity. A steady check engine light, while not immediately alarming, should not be ignored. It often signals minor issues like a loose gas cap or a dirty mass airflow sensor, which, if left unaddressed, could escalate into more significant problems over time. On the other hand, a flashing check engine light is a clear indication of a serious malfunction, such as engine misfires or a failing fuel injection system, which can lead to costly repairs if not dealt with promptly. Additionally, if the check engine light appears alongside other warning indicators, it suggests a more complex issue that requires immediate diagnostic attention. Therefore, whether the light is steady or flashing, taking action sooner rather than later can save you from potential safety risks and expensive repairs, ensuring your Subaru Forester remains reliable on the road.

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