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sean, Car and LCV technician
Category: Peugeot
Satisfied Customers: 3105
Experience:  Technician for 30 years.
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i have a 407 diesel auto and the brake pedal just went solid

yesterday. today it seems to... Show More
yesterday. today it seems to be ok. what would be the problem and is it safe to drive today
Submitted: 3 years ago.
Category: Peugeot
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replied 3 years ago.
Hello, I hope the following assists you.
From the description you've given there is a fault with the vacuum assistance for the brakes. To make the brake pedal easier to press there is a vacuum operated servo, this is supplied with a vacuum by a vacuum pump on the engine, when you press the brake the servo assists making the pedal easier to press. The vacuum system has a one way valve so when vacuum is in the servo and the engine is switched off you still have a vacuum so on restarting the car you have full braking available.
As the pedal seems OK then this would suggest a problem with the valve sticking.
With regard to driving the car I can only say the choice is yours, usually when this happens it's only the first few times after starting the brake pedal is hard. If driving bear in mind if the pedal goes hard it will mean a much greater stopping distance.
I hope this helps but if you have more questions regarding this let me know and I'll reply as soon as I'm able to.
Best wishes,