Temp gauge pegged help

[BRMiller]

Ok needing some help. Water pump went out so replaced it, the thermostat, and the cylinder head temp sensor since I was getting the P1299 code. Filled all new coolant and let it run to get the air out. The temp gauge is still pegged and keeps throwing the P1299 code. Engine is also running rough as if it's in limp mode. Using my scanner to clear the codes and it comes right back on as soon as I clear it. No leaks that I can find anywhere. I can turn the key and the temp gauge is immediately pegged before I even start the car. After letting it sit for a bit, started it back up. Temp gauge maxed right from the start but my scanner shows the ECT at 120 degrees. Any ideas?

 

[Logan97]

Ok needing some help. Water pump went out so replaced it, the thermostat, and the cylinder head temp sensor since I was getting the P1299 code. Filled all new coolant and let it run to get the air out. The temp gauge is still pegged and keeps throwing the P1299 code. Engine is also running rough as if it's in limp mode. Using my scanner to clear the codes and it comes right back on as soon as I clear it. No leaks that I can find anywhere. I can turn the key and the temp gauge is immediately pegged before I even start the car. After letting it sit for a bit, started it back up. Temp gauge maxed right from the start but my scanner shows the ECT at 120 degrees. Any ideas?

Did you replace the cylinder head temperature sensor? I read that could also cause that code