Supercharger Session Communication Interrupted Mid-Charge

Common Symptoms

• Charging session stops unexpectedly mid-charge with no user input
• Touchscreen shows a red or yellow charging error and the charge port light pulses amber or goes solid red
• App notification says charging stopped but does not give a clear reason
• Car does not resume charging after the cable is unplugged and re-seated
• Same error repeats at a different stall on the same Supercharger station
• Charge port latch clicks but the car never enters an active charging state
• Scheduled charging or Trip Planner shows unexpected range shortfall because session ended early

Probable Causes (Ranked by Likelihood)

• Faulty or contaminated Supercharger stall CAN pilot signal line causing handshake dropout Very Likely
• Charge port inlet pins damaged, corroded, or partially seated preventing continuous pilot communication Very Likely
• Intermittent connection in the charge port latch or pilot sense wiring harness inside the car Likely
• Onboard charger (OBC) firmware or hardware fault dropping the ISO 15118 or DIN 70121 Power Delivery Contract mid-session Likely
• VCLEFT or charge port controller software crash resetting the CAN node that manages Supercharger communication Possible
• Foreign debris, moisture intrusion, or bent pin inside the charge port receptacle breaking contact under thermal expansion Possible
• Supercharger station network or cabinet firmware issue affecting only that specific stall Less Likely

Step-by-Step Diagnostic Procedure

1. Start by moving to a different stall on the same Supercharger station. If charging completes normally, the fault is stall-side. Report the bad stall to Tesla via the app. No car repair needed.

2. Try a second Supercharger location entirely. If the error follows the car to multiple different stations, the fault is on the vehicle side. Continue the steps below.

3. Visually inspect the charge port inlet with a flashlight. Look for bent, pushed-back, or corroded pins. Any pin damage means the charge port assembly needs replacement. Do not attempt to straighten pins yourself as the pilot pin is delicate.

4. Check for moisture or debris inside the charge port. If present, use compressed air at low pressure to clear it and let it dry completely before testing again. Moisture on the pilot pin causes exactly this type of intermittent handshake failure.

5. Open the Tesla touchscreen service menu by pressing and holding the brake pedal while holding both scroll wheel buttons for about 10 seconds. Navigate to Service and look for any stored CHARGE or VCLEFT faults alongside CHARGE_a173. Multiple codes together point toward a controller reset rather than a simple connector issue.

6. Use Scan My Tesla with an OBDLink MX+ or Veepeak adapter to pull live charge port pilot voltage. During a normal Supercharger handshake the pilot signal should step through defined voltage levels (12V, 9V, 6V, 3V) as the session negotiates. A signal stuck at 12V or dropping to 0V early means the pilot circuit is open or shorted on the car side.

7. Inspect the charge port door and latch mechanism. A latch that does not fully engage can allow micro-movement of the connector during charging, which interrupts the CAN handshake. Push the connector firmly until you hear two clicks and watch whether the port light holds green.

8. If all stall changes and visual checks fail to isolate the fault, the onboard charger or charge port harness needs bench diagnosis. This requires Tesla Toolbox 3 to flash or reconfigure the OBC and is beyond DIY scope. Schedule a mobile service appointment or visit a Tesla Service Center.

Frequently Asked Questions