This is something I had to do in harsh climates as eventual water and other contaminants build up. Until I lived in this extreme weather I had never had such done but given the age I have to ask. This is not a firm diagnosis but what it could be. This will clean that system out and they will bleed any air out as well.
The SIMPLEST thing you can check is the brake fluid level. It must be to the fill line.
I bought a used, good condition Ford Ka 2005 1.3l a month ago. It drove nicely and with good, solid brakes, making two or three local area journeys a week and taking me 150 miles Southwest to a wedding and back a fortnight ago on the motorways.
On Wednesday night however, it drove me out fine on an 8 mile trip but, halfway home, I had to brake fairly solidly (not emergency stop) and after that point the brakes felt soft. The pedal would travel halfway before the brakes even came on whereas before that'd be full lock. I tried pumping them but that didn't change the feel. At full depress the brakes were fairly strongly applied, enough that I could safely drive home, but there was little resistance. Parked in the garage, I heard a wheezing sound when the pedal was lifted from the floor.
I contacted the dealer who came over Friday evening to take a look but the brakes were magically working fine and I looked a complete idiot! He invited me to take it to them for a proper investigation, so I drove in yesterday and, when I picked the car up that evening, was told they found nothing wrong. The dealer spent £50 on his mechanic to have a look and gets nothing from me, so it's not in their interests to cover anything up or do a poor job AFAICS, unless there's a bizarre and expensive fault they want to avoid.
So the question is, what can cause my brakes to suddenly go soft and spongy and then clear up after a couple of days without any use? My car appears to be working but can I really trust the brakes?
Incidentally my previous (and first) car was a 2002 Toyota Yaris in perfect condition that generated an engine fault which repeatedly didn't appear when mechanics had a look, until after £300 and 6 mechanics having a look and having different theories, was finally diagnosed as having a rare ECU failure. So I've precedent for obscure and expensive problems! ![]()

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