Yuànzi lǐ de cízhuān zāng le, děi ná gāoyā qīngxǐjī chōng yíxià.
The yard tiles are dirty — need to blast them with the pressure washer.
Tips
usage
高压清洗机 covers the whole spectrum from small Karcher-style consumer units (often called 洗车机 if marketed for cars) to industrial models. Don't confuse with 高压锅 (pressure cooker) — same 高压 prefix but a totally different appliance.