Réponse à : « Palm rest temp sensor (TsOP) issue »iSight Disconnect Worked! I disconnected the trackpad, cleaned it, checked cables and fit. Did PRAM and SMC as well. No change after Apple Hardware Test runs. Error message 4SNS/1/40000000: TSoP-128.000 After reading this post, I disconnected the iSight cable, and booted up my Macbook Pro 17" (Mid 2009; 5,2). First thing I noticed: No fans! Ran the AHT and found 0 errors! I did notice both WiFi and Bluetooth were not present in El Capitan (10.11.6), although still physically connected. Reconnected the iSight cable. Fans kicked in on power up. So did the error after an AHT run. I'm going to try replacing the cables. Will report on it! Some links that were helpful to me... - iSight removal video. Helpful for cable identification and removal. However, I don't foresee having to remove the display entirely as depicted. https://www.youtube.com/watch?v=rYyWsz9w... - Online sellers pricing at $5.45 to $8.45 for these cables. http://www.powerbookmedic.com/MacBook-Pro-17-Unibody-iSight-Cable-p-19922.html Wish me luck!