"PID Autotune failed! Temperature to high" (2 replies)

Hi all.
I recently replaced the hot end resistor on my RepRapPro Huxley with a new cartridge heater and nozzle. Afterwords I noticed that, in Pronterface, the hot end temperature tends to oscillate around the set temperature by a few degrees. I figured a PID Autotune would be in order, but when I run the commands, the temperature rises, overshoots (around 30C over), and says PID Autotune failed! Temperature to high. This is the same for all the temperatures I try.

>>>M301 P12.000 I2.200 D80.000 (RepRapPro's/Melzi Defaults)
SENDING:M301 P12.000 I2.200 D80.000 
ok p:12.000 i:2.200 d:80.000 w:125
>>> M303 S150 C8
SENDING:M303 S150 C8
PID Autotune start
PID Autotune failed! Temperature to high
>>> M303 S100 C8
SENDING:M303 S100 C8
PID Autotune start
PID Autotune failed! Temperature to high
>>> M303 S50 C8
SENDING:M303 S50 C8
PID Autotune start
PID Autotune failed! Temperature to high

I tired to manually fiddle around with the PID settings, but I still get the same result. Any ideas?