2006 Sebring Transmission Overheat P0218: Real vs OBD-Read Temperature Discrepancy & PCM Diagnosis

High priority issue — I'm posting from Finland with a 2006 Sebring 2.7L Touring model (137,650 km / 86,031 miles). Recently, my transmission has been showing DTC P0218: 'Transmission Overheat - High Temperature Operation Activated'. The issue began about a month ago when I noticed rough shifting while reversing into my yard. The shift was abrupt and difficult. Upon checking with an OBD-II scanner, the transmission oil temperature reading spiked to 141°C — which caused significant concern. I confirmed the transmission fluid level and condition: it's at proper levels and has no burnt smell (last changed at 3,000 km). The fluid was replaced with Mack 1. This issue has occurred multiple times since then. On the third occurrence, I used a laser gauge to measure actual oil temperature at both the bottom of the transmission and the front of the solenoid pack. The real temperature read between 54–56°C — significantly lower than the OBD-II reading of 135°C. I've since replaced all relevant components: speed sensors, solenoid pack, and Transmission Range Sensor (TRS). Despite these changes, the P0218 code persists. What's strange is that when the actual oil temperature reaches around 56–57°C, the OBD-II scanner suddenly jumps to 141°C — then drops back to about 76°C within minutes. However, my real-time laser measurements confirm normal temperatures at the transmission surface during these events. My key question: Why does the PCM report an overheat condition when actual oil temperature is well below 120°C? Is this a sensor fault, wiring issue, or a deeper problem in the Powertrain Control Module (PCM) or TCM? I don't yet believe the transmission itself is faulty. I've ruled out leaks and confirmed that the transmission cooler is functional. Possible causes based on technical data: - Engine cooling system malfunction (e.g., restricted coolant lines, CK bypass valve failure) - Transmission oil cooler plugged or clogged But given my real-world measurements show normal temperatures, I suspect a faulty sensor or miscommunication in the PCM. The CK bypass valve — which allows coolant flow to bypass the transmission cooler during cold weather — may be stuck open or malfunctioning. However, I don't see any extra lines on my car’s transmission cooler setup. I’ve considered replacing the PCM with one programmed via VIN and part number. While I’ve seen US-based PCMs, I’m unsure if they will function correctly in Finland due to environmental differences (e.g., climate, temperature cycles). I'm seeking expert insight: Could a faulty PCM be causing this false overheat reading? Is there any way to verify this without professional diagnostics or transmission repair? This has been a persistent and frustrating issue — I've had two Grand Caravans before, but never faced such reliability problems with an American car. Still, I love driving it. P.S. No oil leaks. All components are clean and the cooler is confirmed functional.