High Voltage Battery Pack Overtemperature Warning

Common Symptoms

• Touchscreen shows a red or orange battery warning with a temperature-related message
• Supercharger session slows dramatically or stops before reaching your target state of charge
• Regenerative braking is reduced or completely disabled on the energy display
• Maximum power output is noticeably limited, acceleration feels soft or capped
• Climate precondition or cabin cooling runs unusually long before charging begins
• Battery thermal indicator in the energy app shows bars in the red or orange zone
• Car enters reduced-power driving mode even with a full or near-full battery

Probable Causes (Ranked by Likelihood)

• Repeated back-to-back DC fast charging sessions with no cool-down interval, especially in ambient temperatures above 90 degrees F Very Likely
• Extended high-performance driving such as track use, repeated hard launches, or sustained highway pulls that push pack temperatures above safe thresholds Very Likely
• Battery thermal management (BTM) coolant loop low on coolant or not circulating properly, reducing the pack's ability to shed heat Likely
• BTM coolant pump failure or reduced flow, preventing adequate heat transfer away from the cells Likely
• Cabin climate system diverting cooling capacity away from the battery loop during extreme ambient heat, slowing thermal management Possible
• Blocked or damaged undercarriage heat exchanger reducing cooling efficiency at the battery radiator Possible
• BMS temperature sensor fault reporting a false high reading on one or more cell groups Less Likely

Step-by-Step Diagnostic Procedure

1. Pull the full fault list using Scan My Tesla with an OBDLink MX+ or Veepeak adapter. Look for companion codes alongside BMS_a068, especially any codes referencing coolant pump speed, flow rate, or thermal system faults. Screenshot everything before clearing.

2. Check ambient and pack temperature context. Navigate to Service menu (long-press the Tesla logo in About) and look at the BMS live data screen for cell group temperatures. Any single group reading above 50 degrees C (122 F) while parked in shade is abnormal after a 30-minute cool-down.

3. Inspect the battery coolant reservoir under the front hood. It is the smaller of the two reservoirs (the other is for the motor). Level should be between MIN and MAX lines. Low coolant here means the BTM loop is starved.

4. Listen and feel for BTM pump operation. Sit in the car with it powered on and climate running. You should hear a faint hum from the battery coolant pump under the front end. No hum after 2-3 minutes of climate on suggests a failed pump, which requires a shop.

5. Check for coolant leaks. Inspect the underside of the car along the battery pack perimeter and the front cooling module area for any orange-tinted coolant residue or staining. Tesla uses a distinctive orange-dye coolant.

6. Verify the car's precondition-before-charging setting is enabled. In the Charging menu, confirm that the car is allowed to precondition the battery before Supercharging. If this was manually disabled, re-enable it. This feature prevents many BMS_a068 events by pre-cooling before fast charge.

7. If the code returns after a full cool-down in shade (2 or more hours) with no driving or charging, suspect a stuck coolant valve or sensor fault. At this point you need Tesla Toolbox 3 or a trained EV tech to perform a BTM system actuator test. This is beyond what Scan My Tesla can command.

8. Do not attempt to clear BMS_a068 and resume fast charging if the pack has not physically cooled. The BMS will re-flag immediately, and repeated thermal stress accelerates cell degradation.

Frequently Asked Questions