Is it possible to cause damage to cars by jet washing?

My Mercedes CLK280 was recalled for a sunroof check. When I got it back, the auto-lights failed followed by the interior light and then the sunroof. A swathe of lacquer had been taken off the boot where a tiny amount had been off before hence I only washed it gently. It transpires they had jet-washed the car without my permission and this caused the damage forcing water into the circuit board and taking the lacquer off. They dispute this.

In your experience, have you come across this before? Water comes in through the window seals if jet-washed but all the car is water tight in torrential rain etc?

Asked on 17 August 2023 by Sally Willcocks

Answered by David Ross
A badly-handled jet washer can certainly cause this kind of damage. Cars are obviously designed to be waterproof, but a jet washer held too close to a seal can easily result in water entering places it should not thanks to the high velocity of water. As cars age the seals can also become less efficient at keeping out water as they harden. It is also possible to damage paint if it is already in poor condition.
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