AQ8L09U control board - sensor pressure fault leds

[jorgemef]

Hello.

I am trying to troubleshoot what can be the cause of sensor pressure fault received that triggers everytime this washing machine flushes. It is a Ariston/Hotpoint with C00298694 control module.

The microprocessor inside is a HD64F36079LFZ

The pressure sensor is a linear sensor which ranges from 0 to 5V square wave with output of 10,2Hz (with water) to 10,75Hz(flush). Signal attached.
I see the microprocessor VCC line with what seems too much riple. It is regulated from an unregulated 12,4v to 3.3v via an LD33.

Can the ripple be the source for troubles on the microprocessor, or is in an acceptable level?

BR,
Jorge

[jorgemef]

Well, ripple was only because I was used leads to measure the signal. By using oscilloscope probe with ground spring, voltage regulation seems to be in acceptable range.
Will need to check elsewhere if problem persists. Lots of work because of bad measurement/noise from leads.