Brand new here so not sure if i am posting in the right place. Have a totally stock C5. Today the temp gauge spiked to 260. Popped the hood, everything felt normal. Left it shut off for a while. Key on and the dash readout is about 85 degrees Celsius. Start it up and gauge reads 200 for a few seconds and spikes again. And the dash readout says "xxx degrees". Coolant temperature sensor gone bad? Thanks.
Coolant temp spiking
- Thread starter kevinl65
- Start date
That sounds like your temp sensor has packed it in. If it actually got to 260, it likely would have boiled over and pushed past the cap (ask me how I know........ 
). I would also check between the A/C condenser and rad just for good measure, as C5s are bottom feeders and can pick up all kinds of junk in between there that will restrict air flow.
). I would also check between the A/C condenser and rad just for good measure, as C5s are bottom feeders and can pick up all kinds of junk in between there that will restrict air flow.