Vehicle Automatically Parked to Prevent Rollaway
The TESLA-DI_A166 (Tesla Drive Inverter (DI)) EV fault code means: Vehicle Automatically Parked to Prevent Rollaway. This is a low severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- beginner
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What Are the Symptoms of TESLA-DI_A166?
- The car shifts itself into Park while moving very slowly
- On-screen message to fasten the seatbelt and close the door to stay in gear
What Causes TESLA-DI_A166? (Most Likely First)
- Expected behavior: the car decided the driver was leaving or no longer present Very Likely
- A charge cable connected to the charge port, which also shifts the car into Park Possible
Can I Still Drive with TESLA-DI_A166?
Yes, but fix soon. TESLA-DI_A166 is rated low severity. It is not an immediate stop-driving fault, but it will not clear itself — book the repair rather than ignoring it.
Frequently Asked Questions
Why did my Tesla shift into Park by itself?
Tesla calls this rollaway prevention: below 1.4 mph with no recent pedal or steering input, the car parks itself when at least two of these are true: seatbelt unbuckled, driver not detected, driver door open.
Is DI_a166 a fault?
No. Tesla describes it as expected vehicle behavior. Fasten your seatbelt and close the door to stay in gear.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose TESLA-DI_A166?
Tesla shifts into Park when ALL of these are true: Autopark is not active; the car is moving slower than 1.4 mph (2.25 km/h) in Drive or Reverse; and no driver activity (pedals or steering) for more than 2 seconds.
AND at least TWO of these are true: driver seatbelt unbuckled; driver not detected as present; driver door open. The Model S, Model X and Cybertruck manuals add a fourth: a sensor used to detect those conditions (seatbelt buckle, seat occupancy, door latch) is not working as expected.
To stay in gear, fasten your seatbelt and close the door. No repair is needed when this happens for those reasons.
Sources 6
This page is built from documented references. Verify against your own service info before repair work.
- Tesla Model 3 Owner's Manual (2024+, North America, software 2026.20), Troubleshooting Alerts, printed p.275: DI_a166, "Vehicle automatically parked to prevent rollaway / Fasten seatbelt and close door to stay in gear"
- Tesla Model S Owner's Manual (online edition, read 2026-10-23), Troubleshooting Alerts: DI_a166
- Tesla Model X Owner's Manual (online edition, read 2026-10-23), Troubleshooting Alerts: DI_a166
- Tesla Cybertruck Owner's Manual (online edition, read 2026-10-23), Troubleshooting Alerts: DI_a166
- Tesla firmware alert reference (core-hacked/tesla-alerts-dictionary): DI_a166_driverLeftcommunity-maintained dictionary, not an official manufacturer document
- Tessie Tesla alert statisticsthird-party Tesla alert reference with owner-telemetry frequency — not an official Tesla document
Which Vehicles Commonly Get TESLA-DI_A166?
- Tesla Model 3
- Tesla Model Y
- Tesla Model S
- Tesla Model X
- Tesla Cybertruck
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