Hi All,

I noticed a weird behaviour of my 1 year ++ Oscar 2. lately i can't hear the vibration pump sound when i switch on the machine. From my past 18 months with the machine, when i turn on, the pump will normally activated for few seconds to fill up the boiler. However, i no longer hear this sound for the past 2 weeks. However i can still use the machine which the pump is working when i start the brewing process. Has anyone encounter this problem? Is this normal or something wrong with my machine? Any help is very much appreciated. Thanks.

When the pump refills the steam boiler, it fills slightly past the water level sensor. When the steam boiler water cools, it contracts, lowering the water level a tiny bit. Depending on when you power down the espresso machine, the water level will need to be topped off (or not).

When I had an espresso machine on timer, I intentionally forced the steam boiler refill cycle before powering down by draining water through the water tap. That way we wouldn't hear the buzzing of the vibratory pump at 5am. Presumably you're not hearing this usual startup because you (unintentionally) did the same thing.

[Of course, if the steam boiler never refills, that's a problem that needs to be addressed to avoid melting the heating element]

Thanks for the reply. Based on your explanation, the issue might be due to the sensor, where it no longer detect the low water level and the pump will only activate when I pull a shot. The reason I say this is because, I no longer hear the pump sound whenever I turn on the machine, which I normally hear this every time I turn on until 2 weeks ago. Maybe I go and check the sensor cable and see whether any issue with that.

If that's the case, grounding the sensor probe should cause the pump to start immediately.

If you're handy, I would power it down, let the boiler cool completely, and check the boiler water level with a wood dowel by removing a fitting atop the boiler. I would also check for scale buildup on the water level sensor probe. I don't think that's the cause of this specific problem, but scale buildup is often the cause of misbehaving espresso machines.

You are right, once I remove the sensor connector from the boiler and when I turn on the machine, the pump start to work. Is this confirm the sensor need to be replace? Or I need to remove and do some sort of cleaning? Once again appreciate your help to identify the problem. Thanks.

Now I have another problem. Since the sensor didn't work properly for the past 2 weeks. Now I couldn't tell how low the water level inside the boiler. Anyone know how to check Oscar 2 water level inside the boiler? Thanks.

The water level sensor is commonly just a piece of wire stuck through what commonly is a white plastic insulator. If the pump is not turning on it means that piece of wire is conducting electricity to the boiler shell. If it looks like what I'm describing, very gently see if you can turn the connector and if it turns try pulling it up. Again, very gently. If the probe is badly scaled removing it might damage the white plastic piece and you'd need a new one. If you can pull it up, raise it a few cm at a time and then check if the pump turns on. Normally raising the probe will place it above the water level and the pump should turn on.

Thanks. Will try to do that to test the water level.