diff --git a/vllm/engine/llm_engine.py b/vllm/engine/llm_engine.py
index bbdbb2604cf60..747963883bf9a 100644
--- a/vllm/engine/llm_engine.py
+++ b/vllm/engine/llm_engine.py
@@ -1589,7 +1589,7 @@ def create_trace_span(self, seq_group: SequenceGroup) -> None:
             seq_span.set_attribute(SpanAttributes.LLM_LATENCY_E2E, e2e_time)
 
     def is_encoder_decoder_model(self):
-        return self.model_config.is_encoder_decoder_model
+        return is_encoder_decoder_model_config(self.model_config)
 
     def is_embedding_model(self):
         return is_embedding_model_config(self.model_config)