Mobile App Server Connectivity Lost
What does TESLA-UI_A013 mean?
The TESLA-UI_A013 (Tesla) EV fault code means: Mobile App Server Connectivity Lost. This is a moderate severity code.
Common Symptoms
- Tesla mobile app shows 'Unable to connect to your vehicle' or spins indefinitely
- Remote climate pre-conditioning cannot be started from the app
- Charge status and charge stop commands do not update or respond in the app
- Sentry Mode alert notifications stop arriving on your phone
- Scheduled departure and remote unlock features stop working
- Touchscreen shows no LTE signal bars or a grayed-out connectivity icon in the top status bar
- Over-the-air software update downloads stall or fail to begin
Probable Causes (Ranked by Likelihood)
- Poor or absent LTE cellular signal at the vehicle's parking location (fringe coverage area, underground garage, rural setting) Very Likely
- LTE modem firmware glitch or soft crash requiring a reboot of the UI controller Likely
- Expired or suspended Tesla Premium Connectivity subscription cutting off LTE data Likely
- Tesla server-side outage or API maintenance window affecting app-to-vehicle communication Possible
- Faulty or degraded LTE modem hardware inside the vehicle (antenna cable loose or modem failing) Possible
- SIM card provisioning error following a software update that reset modem credentials Less Likely
- CAN bus communication fault between VCFRONT and UI controller preventing network status relay Less Likely
Step-by-Step Diagnostic Procedure
Check the Tesla status page at status.tesla.com from your phone to rule out a Tesla-wide server outage before touching the car. If the servers are down, the fault will resolve on its own.
Sit inside the car and look at the top-right corner of the touchscreen. Check whether LTE signal bars are present. Zero bars or a grayed icon confirms no cellular signal at that location. Drive the car to an open area with known strong LTE coverage and recheck the app connection.
Verify your Tesla app subscription: go to the touchscreen, tap the LTE/connectivity icon, and confirm Premium Connectivity is active and not expired. A lapsed subscription will produce this exact fault with no other symptoms.
Perform a soft reboot of the UI controller. Hold both scroll wheel buttons simultaneously until the touchscreen goes black, then release. Wait 90 seconds for full restart. Check the LTE bars and retry the app. This clears the majority of LTE modem soft-crash faults.
If the reboot does not restore connectivity, perform a full power cycle: park the car, turn off climate, go to Service menu (tap the Tesla T at top center, select Service), and use the Power Off option. Wait 3 full minutes without opening doors, then press the brake to wake the car. This resets deeper modem hardware states.
Open Scan My Tesla using an OBDLink MX+ or Veepeak adapter to read active UI subsystem codes. Look for any companion codes referencing the modem, VCFRONT CAN errors, or repeated UI_a013 timestamps. Frequent timestamps clustered over many locations confirm a hardware modem issue rather than a coverage issue.
Inspect the shark-fin antenna on the roof for physical damage, cracks, or lifting at the base seal. A damaged antenna dramatically cuts LTE receive sensitivity. This requires no tools beyond a visual check from outside the car.
If connectivity fails across multiple locations and after multiple reboots, the LTE modem module or its antenna pigtail connector likely needs replacement. This is an advanced repair requiring partial headliner removal and is best handled by an independent Tesla-capable shop or Tesla service center. Tesla Toolbox 3 can force a modem re-provisioning that aftermarket tools cannot.
Frequently Asked Questions
What does Tesla code UI_a013 mean?
It means the car's internal LTE modem has lost its connection to Tesla's mobile app servers. The car itself works fine and is fully drivable, but remote features like app-based climate, charge monitoring, Sentry alerts, and over-the-air updates all rely on that cellular link. When it is gone, those features stop working.
Can I still drive my Tesla with this code active?
Yes, fully. UI_a013 is a connectivity warning only. It does not affect driving, charging at the car, Autopilot, or any safety system. You just lose remote app control until the connection is restored.
How much does it cost to fix UI_a013?
Often nothing. A touchscreen reboot or moving the car to a better coverage area resolves it for free. If the LTE modem hardware has failed, expect $300 to $600 at a Tesla service center for modem replacement, or $150 to $250 at an independent EV shop for antenna cable work.
Will Sentry Mode still record if UI_a013 is active?
Sentry Mode will still record video to the USB drive as normal because that function runs locally on the car. What you will lose is the push notification to your phone alerting you that an event was recorded. The footage is safe, you just will not get the real-time ping.