Experiencing a check engine light in your 2016 Subaru STI can be unsettling, especially when accompanied by a P0016 code. This OBD2 trouble code, indicating a Camshaft Position Sensor Bank 2 issue, can trigger a cascade of concerns. One Subaru owner’s experience highlights the frustrating journey of diagnosing and resolving this problem, proving that even routine maintenance and warranties can’t always prevent unexpected automotive headaches.
Initially, the owner of a 2019 WRX (experiencing the same P0016 code, similar to what a 2016 STI might face) diligently maintained their vehicle with oil changes every 5000 kilometers (approximately 3200 miles). Despite this proactive approach, the dreaded P0016 code appeared. The dealership’s first assessment pointed towards “dirty oil” and a low oil level, even though the owner consistently monitored and topped up the oil. A costly double oil flush was performed, but the P0016 code persisted.
The diagnostic process then took a deeper dive. Suspecting internal leaks, the technicians discovered faulty exhaust valve seals, allowing oil to seep into the exhaust system. These seals were replaced, along with a sprocket, and even the Engine Control Relay (ECR) was changed due to sprocket misalignment. However, these repairs proved to be insufficient in banishing the P0016 error.
Undeterred, the dealership proceeded with a more extensive investigation. The engine was removed and meticulously inspected, focusing on the AVCS (Active Valve Control System) components. Despite thorough cleaning and examination, no apparent issues were found within the AVCS system. Frustratingly, the problem remained elusive, and the car was returned to the owner while the dealership consulted with Subaru’s technical support.
Further directives from Subaru led to another round of replacements. This time, the oil pump, timing cover, and tensioner were exchanged, and a third ECU was installed, suspecting corrupted data in the previous units. Yet, the P0016 code stubbornly refused to disappear. The car was briefly returned to the owner as the dealership awaited further instructions, highlighting the prolonged inconvenience of such complex diagnoses.
Finally, the breakthrough came during the third engine removal. This time, a critical discovery was made: the camshafts were severely scored. This revelation prompted a comprehensive camshaft replacement, including seals, carriers, another oil pump, and filters. All oil passages were meticulously cleaned once more. Sprockets were readjusted, new seals installed, and a fourth ECU was implemented. After this extensive and persistent effort, the P0016 code finally vanished, and the Subaru STI returned to its normal operation.
This experience underscores the complexity of diagnosing OBD2 codes like P0016. What began as a seemingly straightforward issue led to weeks of troubleshooting and multiple engine interventions. Despite having both factory and extended warranties, the owner faced rental car limitations, as diagnostic time was not covered. The initial oil flush cost was also deemed “maintenance” and not reimbursed. The root cause of the scored camshafts remained unexplained, adding another layer of mystery to this automotive ordeal.
While frustrating, this detailed account serves as a valuable lesson for 2016 Subaru STI owners and beyond. A P0016 code can be more than just a sensor malfunction; it can be a symptom of deeper mechanical issues. Persistent diagnostics and a methodical approach, even when involving multiple steps and component replacements, might be necessary to truly resolve such problems. If you encounter a P0016 code and your dashboard resembles a “christmas tree” of warning lights, be prepared for a potentially lengthy diagnostic process and ensure you advocate for comprehensive investigation, even if it means multiple visits to the dealership.
