Getting your 2008 Subaru WRX ready for an emissions test can sometimes be tricky, especially when dealing with OBD2 readiness monitors. These monitors are crucial for your vehicle’s onboard diagnostic system to function correctly, ensuring your car is running cleanly and efficiently. Understanding and completing the OBD2 readiness cycle is essential for passing your emissions test and keeping your WRX in top shape.
Understanding the OBD2 Readiness Cycle
The OBD2 system in your 2008 WRX, like all OBD2 compliant vehicles, runs self-tests called “monitors” to check various emission control systems. These monitors need to complete their diagnostic checks, and this completion is reflected in their “readiness” status. If these monitors haven’t run or haven’t completed their cycles, your car might fail an emissions test, even if there isn’t a major problem. This is often the case after battery disconnection or clearing trouble codes.
To reset these monitors and allow them to run, you typically need to perform an OBD2 drive cycle. While Subaru-specific drive cycles exist, a generic OBD2 drive cycle can often help reset these monitors. Keep in mind that the effectiveness of a generic cycle can vary, and it’s always best to consult your vehicle’s service manual for the most accurate procedure.
Performing a Generic OBD2 Drive Cycle for Your 08 WRX
Before starting, ensure your 08 WRX meets these preconditions for a successful drive cycle:
- Cold Start: Begin with a cold engine. The coolant temperature should be below 122°F (50°C), and the air and coolant temperatures should be within 11°F (6°C) of each other. Avoid turning the ignition on before the cold start, as this may prevent the heated oxygen sensor diagnostic from running.
Once these conditions are met, follow these steps carefully and always prioritize safe driving and adherence to traffic laws:
- Idle Phase: Start the engine and let it idle in drive for two and a half minutes. Turn on the air conditioning (A/C) and rear defroster during this phase, if your WRX is equipped with them.
- Acceleration and Steady Speed: Turn off the A/C and rear defroster. Accelerate moderately and steadily to 55 mph (88 km/h). Maintain a constant speed of 55 mph for three minutes.
- Deceleration: Safely coast down to 20 mph (32 km/h) without using the brakes. For manual transmissions, do not depress the clutch during deceleration.
- Second Acceleration and Steady Speed: Accelerate again to 55 to 60 mph (88-96 km/h) and maintain a steady speed within this range for five minutes.
- Final Deceleration and Stop: Coast down to a complete stop without braking.
After completing these steps, check your OBD2 monitor status using a scan tool. It may take several drive cycles for all monitors to become ready.
Important Considerations
- Safety First: Always perform the drive cycle in a safe location and obey all traffic laws.
- Not Always Guaranteed: This generic drive cycle might not work for all monitors on your 2008 WRX. Some monitors may require specific driving patterns or conditions.
- Vehicle Specific Cycles: For the most reliable results, consult your 2008 Subaru WRX service manual for the recommended OBD2 drive cycle or consult a professional mechanic.
By understanding and correctly performing the OBD2 readiness cycle, you can increase your chances of passing your emissions test and ensure your 2008 WRX’s diagnostic systems are functioning as intended.
