2009 Cadillac CTS 3.6L Engine - OBD2 Code P0008 and Intermittent Power Loss After Rain or Car Wash

As a mechanic with over 60 years of experience, I recently encountered an issue on my 2009 Cadillac CTS equipped with a 3.6L engine. Approximately two months ago, the check engine light activated following a radiator hose blowout. The vehicle displayed OBD2 diagnostic code P0008, which indicates a suspected stretched timing chain. This seemed unusual given that the heater hose failure occurred just prior to the issue. I initially cleaned all sensor connectors and performed multiple resets of the engine control unit (ECU), hoping to clear the fault. After several drives and reboots, I observed that the P000-8 code only appears intermittently—specifically when the vehicle is washed or during rainy conditions. The symptom typically resolves after about two days of normal driving. When the code activates, the car experiences a noticeable loss of power (approximately 2 to 3 lb drop in oil pressure), along with a distinct labor knock sound. These symptoms suggest an electrical issue rather than mechanical failure. I am currently investigating whether the timing chain tensioner is electrically actuated and if there could be a faulty ground connection affecting sensor readings or ECU communication. Could this code be triggered by moisture-related electrical interference? Any insights from experienced technicians would be greatly appreciated.