Absolutely, you can wash it in a 30-degree program on a gentle setting. Do not tumble dry.
The harness can be removed and cleaned, but not in a washing machine. What you can do is remove the harness and wash it by hand with a damp cloth and an unscented soap. The other plastic components of the car seat can be cleaned by hand as well. Important to note however is that you should not use any cleaning products containing solvents since these can have a negative impact on the plastic and thus the safety of the car seat.