Yes, not following the given word limit can affect your PTE Writing score. The word limit for 'Summarize Written Text' is 5-75 words and the same for the 'Write Essay' type is 200-300 words. Writing less than 200 words or more than 300 words will decrease your score for the latter. Writing less than 120 words or more than 380 words will lead to scoring 0 for your 'Write Essay' response. Similarly, if you write less than five or more than 75 words, your Summarize Written Text response will be scored 0.