Temp gauge to red quckly, then back to normal

[Rookie48]

Hey fellow XOutposters!

I have an issue that is driving me nuts. 2006 X5 3.0i 6MT, engine tune, headers/exhaust.

Since applying an OETune over the latest firmware update for my DME, I’m encountering an issue that I cant seem to solve. Once the engine is fully warm and driving down the highway at 70 to 75 MPH, occasionally the temperature gage will move very quickly into the full red zone, sit there for about five seconds, then come back to normal. Occasionally (not always) it will trigger the service engine soon light, and throw a P0117 or a P0118 code. After logging the situation through the OBDII port, the engine temperature never waivers off of 95°C. Both the engine temperature sensor and the thermostat have been replaced very recently. The electric fan is operating properly. This past week I had my Indie shop (Moonlite Motorwerks, these guys rock) verify the software version as there was a TRB against this issue way back in 2006. The firmware version is the latest available.

I can only think there is something in the OE tune package that is causing this issue. Since the truck is not overheating, it’s not a big deal – but where I live in New Jersey this issue is occasionaly triggering the readiness test to “not ready “.

Next step is to remove the tune and see if the issue disappears. If so then I need to go back to the OETune folks to see if they are aware of such an issue.

Has anybody out there experienced this temp gauge going quickly to red and then returning to normal within a few seconds?