2007 MCS 6MT. So a few weeks ago I was receiving P0117 (coolant temp too low) and I shut the code off. Stayed off for a week or so. Comes on. Reset light again. The car ran fine through all of this (engine coolant temp at correct temp on live data). I notice a coolant leak a few days later and the CEL back on. Now it is reading for a P0118 (engine coolant temp sensor circuit too high). I replace the water outlet housing, bleed the system and clear the code. Same issue (car reads 285.5 F on startup) . No leaks. I replace the housing again as there is no leaks and the sensor is reading no resistance. New housing, no leaks and resistance at the sensor. Notice the connector is busted. Repin new OEM connector and plug it in. Full of coolant. Bled it once. Everything is now as it should be. The car warms up and has heat, but just runs in limp mode due to the P0118 code. Clear the code. Light stays off. Cars runs as it should as I run errands. It's about 10 degrees here (F). I get back in the car and the CEL is back on and driving in limp mode. I'm a mile down the road and the coolant temp lights begin flashing (both yellow and red as if its overheating) and no heat. Drive the car the mile home. Nowhere near warm. I'm back at square one now and am stumped as to why I'm still receiving the light. Any help appreciated.

 

Going to move you to the Stock Problems/Issues area, should get more views there.

 

If you get no heat inside the cabin, the water pump is out. Do the pipes get warm of hot os just stay cold? If cold then water pump.

 

Heat gets hot as it should. Takes awhile, but it gets hot.

 

air pocket? did you open the bleed screw to see if any air came out?