GMC Acadia Check Engine Light & Failed System Monitors

I own a 2015 GMC Terrain and encountered a similar situation with the check engine light and incomplete readiness monitors. Having some experience with OBD diagnostics, I can share my recent experience. The onboard diagnostics showed incomplete system readiness after I had disconnected the battery for maintenance. It took about 100km of normal driving for all monitors to complete their self-tests. No actual repairs were needed since this is normal behavior after disconnecting power or clearing codes. To help with your specific case, could you share: Has your battery been recently disconnected? Were any recent repairs performed? What specific OBD codes are showing up? Are you planning an upcoming emissions test? The incomplete readiness status itself is not always indicating a fault, sometimes the car just needs to complete its diagnostic cycles. However, if specific error codes are present, that would point us toward particular systems needing attention. I paid 0 Euro for my situation since it only required the normal drive cycle to resolve. But if your case shows actual fault codes, the repair approach would be different and costs would vary based on the affected components.

Yes, my vehicle readiness monitors returned to normal after the workshop performed a computer reset and cleared the codes. They found that my mass airflow sensor was sending incorrect signals, causing the system to run rich. The repair cost was 280 Euro including diagnostic time. For reference, this was done during my latest service at 109369 KM. The vehicle inspection also revealed that all exhaust components were in good condition, ruling out catalytic converter issues. Running a full onboard diagnostics scan after the repair showed all systems functioning properly. I suggest getting a professional check engine diagnosis to pinpoint the exact cause rather than just clearing the codes, as the issue might return if there is an underlying problem.

Thanks for sharing your repair experience. Its good to hear the mass airflow sensor was identified as the root cause. On my Terrain, I initially thought clearing the codes would fix everything, but learned its important to complete proper OBD diagnostics. After my computer reset last month, I made sure to follow the full drive cycle protocol to restore system readiness. One key difference from your case was that I had no faulty components, just needed the monitors to complete their self-tests. Having dealt with both scenarios now, I fully agree about getting professional diagnostics rather than just clearing codes. Without proper testing, issues like the faulty mass airflow sensor you experienced could go undetected and potentially cause more expensive problems with the exhaust system over time. The 280 Euro repair cost seems reasonable considering it included both diagnostic time and sensor replacement. Much better than risking catalytic converter damage from running too rich.

Thank you everyone for the advice. After getting my mass airflow sensor replaced and completing the necessary drive cycle, my Acadia is running perfectly now. The 280 Euro repair cost was worth it since the check engine light has not returned. The onboard diagnostics experience taught me that while computer reset and code clearing can sometimes help, professional car diagnostics are essential for identifying actual component failures. My workshop did a thorough job checking both the sensor and exhaust system during troubleshooting. For others facing similar issues, make sure to get proper testing done instead of just clearing codes. The initial error message led to discovering the faulty mass airflow sensor before it could cause more extensive damage. Even though my readiness monitors took some time to complete their checks after the repair, all systems are now showing normal operation.