Answer
Jun 08, 2025 - 08:45 PM
It’s always tricky to troubleshoot a vehicle remotely — especially without knowing the car’s mileage, service history, whether it uses a traditional key or a Smart Key system or exactly what led up to the issue. That said, here are a few possible starting points:
If your RX400h uses a traditional metal ignition key, the most common causes are:
- The steering wheel lock may be engaged — try gently turning the steering wheel left and right while turning the key.
- A worn-out or slightly bent key can prevent turning. Try a spare key if available.
- The ignition cylinder itself might be worn or seized, especially if lubrication hasn’t been maintained.
If your RX400h uses a Smart Key system, then:
- A faulty immobilizer, steering lock control unit, or a missing/weak key fob signal could prevent the ignition xxxx from turning at all.
- In rare cases, a faulty brake pedal switch can also stop the system from engaging.
On both systems, a faulty transmission range sensor may also lock out the ignition as a safety feature. This is actually quite common.
Beyond that, the best way to diagnose it is with a proper troubleshooting guide — and that’s where the manual comes in. It includes the same diagnostic charts and step-by-step procedures that Lexus techs use, so you’ll know exactly what to test and in what order. Definitely the fastest way to avoid guessing.
