Guys, just took the 2010 GT3RS out for spring exercise after winter garage time and during engine warmup while driving (h20 at 175, oil at 150) got a "check engine warning-visit workshop" , returning home, Durametric code reader shows a "B0121-cooling system implausible signal" as well as a C190 code-fault instrument cluster. Actual temperatures read reasonable. Car runs fine. Any ideas? Car was to dealer last fall TWICE for this ck eng fault-they clear and say no problem found. Since I have to load the car and tow to dealer and spend much time for no apparent help, I wonder if anyone else has seen this problem. Car has 5000 miles, half on track.
Thanks for help.

 

See this thread and follow the links referenced in it.
https://rennlist.com/forums/997-gt2-...re-sensor.html

 

BigT, how comfortable are you getting underneath the car. DIY replacing the pneumatically operated coolant valve is simple once you have car up in the air. Lift would be ideal, but doable on jackstands.

 

Thanks for quick response on ideas. I had previously checked the vacuum to the transmission mounted valve and watched it operate as temperatures rose, but have not taken valve apart to insure proper sealing-- easy to get to on my lift. However I am suspicious that there is some other cause.

The two temperature gages react normally during heat up with water temp rising much quicker than oil temp-this is confirmed when monitoring actual values during warmup with Durametric tool as well. Eventually oil does rise to water temp. Only unusual occurrence is that the water temp gage NEVER rises above 175 degrees-even on track when oil will exceed 200. Seems strange but dealer says "gages just not accurate" although my Cayenne, etc runs at about 201 degrees water when fully warmed and Durametric reads values above 175 on GT3. Since Durametric reads what appear to be normal temperatures, I suspect sensors are ok, but will check connections for intermittent problem.

Any ideas on max indicated water temp of 175?
Will discuss with dealer one more time and report back.
Thanks, Tom

 

The water temp will go past 175 if you get the car hot enough. It's got a wide range that it indicates 175. My BMW's are the same where they read the middle until they're really hot, then start to creep up...