I have a problem with the P1621 error and not delete it until the engine is working perfectly when removed shall cease to read the oxygen sensors, this is disconnect the battery until 15 minutes. And all be well at times one day, sometimes a week and sometimes two hours. Yes Decide as it gets when the engine will not start at first key is turning, because the starter will not start. And as soon as the engine will not start at first turn the key is taking an error P1621.

 

what jag do you have? Maybe you posted in the wrong forum? a p1621 code is not a code found on the x300 vehicles

 

Update...not listed in my list of fault codes but actually is a fault code, though more common to GM vehicles. Likely a bad ECM/PCM

 

x300, 3,2 sovereign

 

Hi

Did you manage to get that sorted, I too have a P1621 error code and stalling behavior