Experiencing issues with your 2005 Subaru Forester failing its smog test after a battery disconnect? You’re not alone. Many Subaru owners face this situation, especially after battery replacements or engine work. The culprit is often the car’s On-Board Diagnostic System (OBDII) needing to reset its “readiness monitors”. These monitors, including the Evaporative System monitor, need to complete a “drive cycle” to ensure all systems are properly functioning for an accurate smog test.
Understanding the OBDII Drive Cycle for Your 2005 Subaru Forester
The OBDII system in your 2005 Subaru Forester is designed to continuously monitor various engine and emission control components. When the battery is disconnected, or certain repairs are performed, these monitors are reset to a “Not Ready” state. Before your vehicle can pass a smog test, these monitors must complete their self-tests and switch to a “Ready” state. This process is known as an OBDII drive cycle.
For 2005 Subaru Foresters, and many other vehicles, a specific drive cycle procedure is required to trigger these self-tests. The Evaporative System monitor, as mentioned in the original scenario, is a common monitor that often requires a drive cycle to reset after a battery disconnection.
Performing the Subaru Forester OBDII Drive Cycle: Step-by-Step
While the exact drive cycle can vary slightly depending on the specific model year and engine, here’s a general procedure that is effective for many 2005 Subaru Foresters. It’s crucial to perform this procedure safely and on public roads where traffic laws can be obeyed.
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Start with a Cold Engine: Ensure your Subaru Forester’s engine is completely cold. This typically means letting it sit overnight or for at least several hours.
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Start the Engine and Idle: Start the engine without touching the accelerator pedal. Let the engine idle for approximately 2 to 3 minutes. This allows the engine to warm up and begin its system checks.
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Accelerate to Cruising Speed: Gently accelerate to a speed between 45 and 55 mph (72 to 88 km/h). Maintain this speed for about 5 to 7 minutes of steady driving. Avoid sudden acceleration or deceleration during this phase.
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Decelerate and Coast: Safely release the accelerator pedal and allow the vehicle to coast down to 20 mph (32 km/h) without applying the brakes if possible.
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Accelerate Again: Once you reach 20 mph, gently accelerate back up to the 45-55 mph cruising speed and maintain it for another 5 minutes.
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Repeat Coast Down: Again, safely release the accelerator and coast down to 20 mph without braking if possible.
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Idle Again: After the coast-down, bring your Subaru Forester to a stop in a safe location. Let the engine idle for another 2 to 3 minutes.
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Turn Off the Engine: Turn off the engine and allow the vehicle to sit for a few minutes.
Tips for a Successful OBDII Drive Cycle
- Safety First: Always perform the drive cycle in a safe location where you can legally and safely perform the driving maneuvers.
- Smooth Driving: Avoid aggressive acceleration, hard braking, and sudden changes in speed. Smooth and consistent driving is key.
- Monitor Readiness: If you have access to an OBDII scanner, you can check the readiness monitor status before and after performing the drive cycle. This can help you determine if the cycle has been successful.
- Multiple Attempts: It may take more than one drive cycle to reset all monitors. As the smog technician suggested, performing the drive cycle 4 or 5 times is not uncommon.
- Check Engine Light: If the “Check Engine” light comes on during the drive cycle, it indicates a problem. You’ll need to diagnose and address the fault code before proceeding with the smog test.
What if the Drive Cycle Doesn’t Work?
If you’ve performed the OBDII drive cycle multiple times and your 2005 Subaru Forester’s monitors are still “Not Ready,” there could be underlying issues. It’s recommended to:
- Consult a Professional: Take your vehicle to a trusted mechanic or Subaru dealership. They can use professional diagnostic tools to identify any fault codes or issues preventing the monitors from resetting.
- Check for Fault Codes: Even if the “Check Engine” light isn’t on, there may be pending fault codes that are preventing monitor readiness. An OBDII scanner can reveal these codes.
Successfully completing the OBDII drive cycle is often the key to passing a smog test after a battery disconnect or engine work on your 2005 Subaru Forester. By following these steps and tips, you can increase your chances of getting your vehicle ready for its next smog inspection.
