A 2019 Chevy Trax with a P2135 code often leads to a "symptom fix" like a new throttle body. But at 100k miles, oil found in the intake points to a deeper PCV failure. When the intake manifold check valve fails, turbo boost ruptures the valve cover, forcing oil to foul the sensors. We ruled out electrical ghosts like terminal fretting to fix the root cause. This proactive care protects the turbo and prevents recurring Limp Mode.