If your 2022 Toyota Highlander won't start after driving through flooded water, the engine may have ingested water causing hydrostatic lock, or electrical systems may be damaged from water intrusion. Do not attempt to start the engine until the situation is properly assessed.
Understanding Hydrolock
Engines compress air, which is compressible. Water is not compressible. If water enters the engine through the air intake, the pistons cannot complete their stroke, causing catastrophic internal damage - bent connecting rods, cracked pistons, or worse. This is called hydrostatic lock or "hydrolock."
Signs of Water Ingestion
The engine suddenly died while in water. The engine makes unusual clunking sounds when trying to start. The starter engages but the engine doesn't turn over smoothly. Water drips from the exhaust pipe. Any of these indicate possible water in the engine.
What NOT to Do
Do not attempt to start the engine - this can cause or worsen hydrolock damage. Do not drive the vehicle even if it seems to start - internal damage may be present. Do not let anyone crank the engine repeatedly trying to start it.
Proper Response
Have the vehicle towed - do not drive it. A mechanic must remove spark plugs and check for water in cylinders. The air intake and air filter must be inspected. Engine oil should be checked for water contamination. Only after professional assessment should any starting be attempted.