E27 Power supply (POS) sensor fault
This is generally related to the cam or crank sensors
you can try to replace one or the other but it is better if you replace both as a pair. They both work together and sometimes it is difficult to determine which one is actually causing the fault.
I would also pay close attention to the pig tails on the sensors and make sure there are no broken wires where the wires go into the sensor, this is a known issue with wires breaking near the sensors, especially if there is a bend in the harness. If you tug on the wires and any of them are broken you will see it pull and stretch. If you find any broken you will need to get a pigtail replacement that cat did have at some point that they came out with after the problem was discovered and they came up with these repair kits.
As for manually clearing the codes, there is a thing called the 'pedal dance' where you do a specific routine with the key, ignition on/off and accelerator pedal presses in a timed sequence that can gain you access to the stage 2 level and will show you all stored faults and give you the option to clear the 'inactive' codes.
It has been posted many times on this forum and a quick search for that will give you what you need. Just remember that 'pedal dance' routine is a specific timed routine and may take more than once to get into it successfully. Every time i did it i had to attempt it at least twice to get in. Patience, a watch or some timing device is helpful when doing it.
I also heard there is a way to use an OBDII handheld scanner to hook up to the OBD plug located under the cupholder where the CAT diagnostic plug is but i never tried that so i won't be much help with that. But that OBD plug is present, usually wrapped in blue tape (if no one has removed the tape that is).