If your 2018 Toyota Camry displays a P0305 code, diagnosis depends on your engine. The 2018 Camry launched the current generation with both four-cylinder and V6 options. P0305 only applies to V6 models.
V6 Camry: Understanding P0305
In the 3.5L V6, cylinder 5 is on the rear of the left bank. At this vehicle age, ignition component wear is common. Spark plugs may be due for replacement.
Four-Cylinder Camry: Anomalous Code
If your 2018 Camry has the 2.5L four-cylinder, P0305 indicates a diagnostic anomaly—possibly sensor degradation due to age.
Diagnostic Approach
Confirm your engine type first. For V6: inspect cylinder 5 ignition components and consider age-related wear. For 4-cylinder: investigate sensor and wiring condition.