With steamer on, I watch the temperature exceed 155degree celsius on the PID before the PID eventually flashes A2.
Even with the +/- 10c leeway on the thermostat, that temp still seems too high.
The PID seems pretty accurate, as I watch the blue stream light turn off at 116c or so on the display.

I'm going to try replace the 140c steam thermostat (given it is only cheap) and see if I can see the PID stop around that 140c mark and not report an A2.

The pump itself seems to be fine, but without a manometer/pressure gauge it is hard to know.

I haven't been able to replicate the pump failure - that being said, I'm conscious now of watching the PID and if it gets too hot I'm releasing water/steam/pressure.

patcof1 wrote:The PID in the PL41PLUST can never control the pump. The PID only controls the heating element in the boiler in brew mode.

What happens though if the 165c safety thermostat is triggered? Does it cut power to the pump as well as the boiler, or just the boiler?

If I wanted to know the answer to this question in my machine, then I would test this by removing the wires from the 165c safety thermostat and see what happens to the functions. (First unplug the main power from the machine, everyone should always be very careful when working inside espresso machines and take safety precautions).
If I understand the wiring correctly, if the 165c safety thermostat is triggered, it normally cuts power to the boiler heating element and to the pump and to the PID unit (PID display remains dead).

mshannon wrote: I'm going to try replace the 140c steam thermostat

I hope you can let us know in detail what was the cause of the symptom you found on your PL41PLUST.

Just a quick update - changed 140c thermostat over and haven't experienced any issues since. PID temperature seems to max out now around 143c when in steam mode - compared with over 155+ using the previous one when it would eventually flash the error code.

I also descaled the machine thoroughly and think that was contributing to some issues. I may end up replacing the pump - or at the very least pulling it apart.

mshannon wrote:Just a quick update - changed 140c thermostat over and haven't experienced any issues since. PID temperature seems to max out now around 143c when in steam mode - compared with over 155+ using the previous one when it would eventually flash the error code.
I also descaled the machine thoroughly and think that was contributing to some issues. I may end up replacing the pump - or at the very least pulling it apart.

Good job.
A flashing error code A2 on the PID unit can not be related to the symptom of intermittent not starting pump. Error code A2 only means that the PID software decided that the signal coming from the temperature probe is out of range (Boiler too hot or temperature probe defective).