I showed my local dealer the thread. First they replaced just the temperature sensor, which didn't correct the problem. They then agreed to replace the auxiliary water pump, and problem corrected!

Seems like the techs are willing to figure it out, based on the initial "error code" they decided to replace the air temp sensor. When that didn't fix the problem they further researched the issue, along with the info in this thread, and agreed to replace the auxiliary water pump. I'm glad they did, it's just a shame they couldn't diagnose the problem with the "error code" from the car's computer.

Thanks to this forum and their willingness to agree to replace the auxiliary water pump I'm back to enjoying the SRT-6.