Understand Tesla alerts — what they mean, how urgent they are, and what to check.
⛔ vehicle_may_not_restart — Vehicle may not restart
Critical
What it means: The low-voltage (12V) system is unable to maintain enough power to restart the vehicle after shutdown. Often precedes 12V battery failure.
Affected models: all models
Safe owner checks: If you are driving, continue to a safe location and do not power the vehicle off unless necessary. Do not leave the vehicle powered off unattended for long. Avoid using the touchscreen functions that drain the 12V system.
Owner context: Owners typically see this when the 12V battery is aging (3–4+ years) or after deep discharge. Tesla historically recommends 12V replacement in this state.
When professional service is appropriate: Contact Tesla Roadside Assistance or schedule service to replace the 12V battery.
🔴 low_12v_battery — Low 12V battery / 12V battery needs service
High
What it means: The auxiliary battery voltage is low. The 12V battery powers the touchscreen, computers, and contactors; a failing unit can cause unpredictable behavior.
Affected models: all models
Safe owner checks: Minimize accessory use. If the vehicle is parked, charge it if possible. Do not ignore the alert — a dead 12V battery can leave the vehicle unable to open doors or start.
Owner context: A common lifespan is 3–5 years. Cold weather accelerates failure.
When professional service is appropriate: Schedule service for 12V battery replacement.
🟠 climate_unavailable — Climate controls unavailable
Medium
What it means: HVAC is not responding — a software or hardware state.
Affected models: all models
Safe owner checks: Try toggling climate from the app. Restart the vehicle when parked. If the cabin is very hot/cold, open windows or use vents until resolved.
Owner context: Often clears after a software restart. Repeated failures point to HVAC hardware.
When professional service is appropriate: If it recurs, schedule service.
🟠 nav_sd_card — Navigation data error
Medium
What it means: Navigation maps cannot be read — usually a corrupted map update.
Affected models: all models
Safe owner checks: Restart the vehicle when parked. Ensure the vehicle completes map downloads on Wi-Fi. Check for a pending software update.
Owner context: Usually fixed by a map re-download or software update.
When professional service is appropriate: If it persists, schedule service.
🟠 power_reduced — Power reduced / limited power
Medium
What it means: The vehicle is limiting motor power, often to protect the battery or drivetrain. Can appear with battery temperature extremes, low state of charge, or a detected fault.
Affected models: all models
Safe owner checks: Continue driving gently if it is safe to do so. Note whether the message appears at low state of charge or extreme temperatures. Check tire pressure — low pressure can trigger derating on some trims.
Owner context: Most occurrences are temporary and related to battery temperature or very low charge. Repeated occurrences warrant diagnosis.
When professional service is appropriate: If power reduction persists, repeats often, or is accompanied by other alerts, contact Tesla Service.
🟠 tpms_low — Tire pressure low
Medium
What it means: One or more tires is below the recommended pressure, detected by the tire pressure monitoring system.
Affected models: all models
Safe owner checks: Check pressures with a reliable gauge when tires are cold. Compare to the label on the driver's door pillar. Inflate to spec. If a tire loses pressure repeatedly, inspect for a puncture or leak.
Owner context: Pressures drop in cold weather and can trigger TPMS. The vehicle shows per-tire pressure on the tire service screen.
When professional service is appropriate: If a tire cannot hold pressure or sidewall damage is visible, have it inspected.
🟠 bms_a029 — Unable to charge
Medium
What it means: The battery management system has limited charging. This can be caused by extreme battery temperature, a faulty charge port or cable, or a BMS fault.
Affected models: all models
Safe owner checks: Park in a safe place and retry with a different cable or charger. Check that the charge port and plug are clean and fully seated. Let the battery cool or warm if the message mentions temperature. Try a different charger to isolate the cable.
Owner context: Owners commonly report this after a failed latch, a dirty connector, or extremely cold/hot battery. It usually clears when the condition resolves.
When professional service is appropriate: If it persists across chargers and temperatures, schedule service — the charge port or onboard charger may need inspection.
🟠 unable_to_charge — Unable to charge — check charge equipment
Medium
What it means: The vehicle did not start charging with the connected equipment.
Affected models: all models
Safe owner checks: Reseat the connector firmly. Try another charger or cable. Check the charging screen for a temperature or configuration reason. Check for debris in the charge port.
Owner context: Most cases are cable/latch related. Intermittent faults can also come from a worn outlet or adapter on mobile connectors.
When professional service is appropriate: If it fails across multiple chargers, schedule service.
🟡 tpms_fault — Tire pressure system fault
Low
What it means: The TPMS cannot read one or more sensors — often after tire rotation, wheel swap, or sensor battery failure.
Affected models: all models
Safe owner checks: Drive briefly — the system may re-sync. Check that pressures are correct with a manual gauge in the meantime.
Owner context: Usually resolves after a short drive; persistent faults often mean a sensor battery needs replacement.
When professional service is appropriate: If the fault persists after several drives, schedule service.
🟡 wall_connector_reduced — Wall connector reduced output
Low
What it means: A wall connector is delivering less power than its rated output, often due to wiring, temperature, or grid voltage.
Affected models: all models
Safe owner checks: Note the delivered amperage on the charging screen. This can be normal during heat. If it persists, have an electrician verify the circuit and torque of connections.
Owner context: Heat-related derating is common in garages in summer.
When professional service is appropriate: If the connector repeatedly derates, inspect the installation.
🟡 wiper_fluid_low — Wiper fluid low
Low
What it means: Washer fluid level is low.
Affected models: all models
Safe owner checks: Top up with washer fluid rated for your climate. Do not use plain water in freezing temperatures.
Owner context: —
When professional service is appropriate: Not a service item.
ℹ️ autopilot_unavailable — Autopilot / safety features unavailable
Informational
What it means: Camera or sensor input is degraded — blocked cameras, glare, fog, or a temporary system issue.
Affected models: all models
Safe owner checks: Keep the windshield and camera areas clean and free of ice/frost. The features usually return when visibility improves. Restarting the vehicle (safety check: only when parked) clears many temporary states.
Owner context: Owners commonly see this in heavy rain, snow, or direct sun. Persistent failure after cleaning may indicate hardware.
When professional service is appropriate: If unavailable for days despite clean cameras, schedule service.
ℹ️ battery_heater_active — Battery heater active
Informational
What it means: The vehicle is warming the battery to enable faster charging or better performance.
Affected models: all models
Safe owner checks: No action needed. Energy is being used to heat the battery — this can reduce displayed range temporarily.
Owner context: Normal during preconditioning and cold-weather charging.
When professional service is appropriate: Not a service item by itself.
ℹ️ camera_blocked — Camera blocked or blinded
Informational
What it means: One or more cameras cannot see clearly. Check for dirt, ice, stickers, or aftermarket film over camera housings.
Affected models: all models
Safe owner checks: Inspect and clean camera covers. Remove anything covering them. The warning clears once the view is restored.
Owner context: Frequent in winter and after car washes.
When professional service is appropriate: If it persists, a camera may need service.
ℹ️ charge_port_open — Charge port open
Informational
What it means: The charge port door is open (informational).
Affected models: all models
Safe owner checks: Close it from the touchscreen if desired. It may reopen when charging is expected.
Owner context: —
When professional service is appropriate: Not a service item.
ℹ️ charge_rate_limited — Charge rate limited
Informational
What it means: Charging speed is reduced, typically due to battery temperature, shared site load, or charging limits set in the app/vehicle.
Affected models: all models
Safe owner checks: No action needed. Expect slower charging until the condition clears. Precondition the battery for Supercharging when navigating to a Supercharger.
Owner context: Charge rate limits are normal at very low or very high temperatures and near full state of charge.
When professional service is appropriate: Not a service item by itself.
ℹ️ app_charge_complete — Charging complete
Informational
What it means: The vehicle reached its target charge level.
Affected models: all models
Safe owner checks: No action needed.
Owner context: —
When professional service is appropriate: Not a service item.
ℹ️ cruise_unavailable — Cruise control unavailable
Informational
What it means: Cruise/TACC cannot engage — often due to degraded camera view, sensor fault, or a temporary system state.
Affected models: all models
Safe owner checks: Check camera visibility. Try again after a short drive. Restarting the vehicle when parked clears many transient states.
Owner context: Usually transient.
When professional service is appropriate: If persistent, note when it occurs and schedule service.
ℹ️ lane_departure_unavailable — Lane departure warning unavailable
Informational
What it means: Lane-keeping features are temporarily unavailable, usually due to camera view or road markings.
Affected models: all models
Safe owner checks: Clean cameras. The feature returns when conditions improve.
Owner context: Common on faded markings and in bad weather.
When professional service is appropriate: Not a service item by itself.
ℹ️ regenerative_braking_limited — Regenerative braking limited
Informational
What it means: Regen is reduced or unavailable, usually when the battery is cold or near full charge.
Affected models: all models
Safe owner checks: No action needed. Braking is handled by the friction brakes; adapt following distance in the meantime.
Owner context: Common in winter and at high state of charge.
When professional service is appropriate: Not a service item by itself.
ℹ️ sentry_unavailable — Sentry Mode unavailable
Informational
What it means: Sentry Mode cannot arm — often low battery state of charge, a system fault, or a temporary state.
Affected models: all models
Safe owner checks: Check state of charge and enable Sentry from the app or vehicle. If the vehicle is below the required charge level, charge it.
Owner context: Sentry disables below roughly 20% state of charge by default.
When professional service is appropriate: If it will not arm at healthy charge, schedule service.
ℹ️ usb_not_recognized — USB device not recognized
Informational
What it means: The connected USB drive is not detected or not formatted correctly.
Affected models: all models
Safe owner checks: Reformat the drive (exFAT/FAT32 as recommended) and reseat it. Use the correct port for data.
Owner context: Some USB drives are incompatible with dashcam/sentry recording.
When professional service is appropriate: Not a service item.
This decoder is a reference for understanding alerts. It is not a substitute for the Tesla Owner's Manual or professional service. When in doubt about a safety-related alert, contact Tesla Service or Roadside Assistance.