Charge Rate Limited by Pack Temperature
What does TESLA-BMS_a071 mean?
The TESLA-BMS_a071 (Tesla BMS (Battery Management System)) EV fault code means: Charge Rate Limited by Pack Temperature. This is a moderate severity code.
Common Symptoms
- Supercharger or DC fast-charge speed is noticeably slower than usual, often shown as a reduced kW ceiling on the charging screen
- Touchscreen displays a message like 'Charging Speed Reduced' or 'Charge Rate Limited' near the charging animation
- Estimated charge completion time is much longer than past visits to the same Supercharger
- Battery temperature indicator in the energy or charging app shows pack is very cold (below about 50°F / 10°C) or very hot (above about 104°F / 40°C)
- BMS_a071 appears in the active alerts list viewable via Scan My Tesla or TM-Spy
- Car feels sluggish on acceleration shortly before or after the limited charge session due to thermal derating
- Preconditioning was not activated before arriving at the Supercharger, and outside temperature is extreme
Probable Causes (Ranked by Likelihood)
- Pack too cold on arrival, no preconditioning, battery cannot accept full current until warmed up Very Likely
- Pack too hot from sustained high-speed highway driving immediately before plugging in, BMS throttles input to protect cells Likely
- Thermal management fluid circuit is low or degraded, reducing the pack's ability to regulate temperature quickly Possible
- Cabin overheat protection ran for an extended period and raised pack temperature above the fast-charge threshold Possible
- Coolant pump for the battery thermal loop is failing or intermittent, causing uneven cell temperatures that trigger conservative charge limits Possible
- BMS cell group imbalance causing the algorithm to interpret localized heat as a whole-pack thermal event Less Likely
- Software bug or stale BMS calibration holding an artificially low charge ceiling even after temperature normalizes Less Likely
Step-by-Step Diagnostic Procedure
Before anything else, open the Tesla app or touchscreen and check the battery temperature readout. Navigate to Controls, then select the charging screen or use Scan My Tesla to read the exact pack temperature. If it is below 50°F (10°C) or above 104°F (40°C), temperature is the direct cause and no hardware fault exists.
Check whether you routed navigation to the Supercharger before arriving. Open the Tesla navigation, search for the Supercharger, and select 'Set as Destination'. The car starts preconditioning the pack automatically. If you skipped this step, that is the most common reason for BMS_a071.
If the car was parked in extreme cold overnight, use the Tesla app's 'Schedule' or 'Precondition' feature to warm the cabin and pack 30 to 45 minutes before departure. Plug into a Level 2 charger while doing this so the car uses wall power rather than draining the pack.
After a long highway drive in hot weather, park in shade and wait 15 to 20 minutes before plugging in. The BMS will use the coolant loop to shed heat. Watch the charge rate on the touchscreen. If it climbs back toward the rated peak within a few minutes, the hardware is fine.
Connect Scan My Tesla using an OBDLink MX+ or Veepeak OBD adapter and look at the BMS cell temperature min/max spread. A spread greater than about 10°F (5°C) between the coldest and hottest cell group suggests the thermal loop is not circulating properly. Note the exact values.
Inspect the coolant reservoir for the battery thermal loop. It is located in the front trunk area on most Model 3 and Model Y cars. Check the fluid level and look for any pink or orange discoloration, which signals contamination. A low reservoir can reduce cooling efficiency significantly.
If the charge rate stays capped well below the rated peak even after the pack reaches a normal temperature range (roughly 60 to 90°F / 15 to 32°C), and Scan My Tesla still shows BMS_a071 active, the coolant pump or a flow sensor may need inspection by a shop with Tesla Toolbox 3. That tool can command the pump on and off and verify flow rates, which is beyond what aftermarket adapters expose.
Frequently Asked Questions
What does Tesla code BMS_a071 mean?
It means the Battery Management System has detected that the pack temperature is outside the ideal window for fast charging, usually too cold in winter or too hot after a long drive, and it has reduced the maximum charge rate to protect the cells from damage. It is not a hardware failure by itself. It is the BMS doing its job.
Can I still drive and charge with BMS_a071 active?
Yes, you can drive and charge. The car will still accept charge, just at a slower rate than normal. Drive performance may also be slightly reduced if the pack is very cold or hot. Both limits lift automatically once the pack returns to the normal temperature range.
How do I prevent BMS_a071 from happening at the Supercharger?
Always route to the Supercharger using the in-car navigation, not a third-party map app. When Tesla is the navigator, it starts warming or cooling the pack automatically while you drive so it arrives at the target temperature. This feature is called battery preconditioning and it is built in. No extra steps needed beyond using Tesla navigation.
How much does it cost to fix?
If the root cause is simply cold or hot temperature with no hardware fault, the cost is zero. Changing the habit of routing via Tesla navigation before Supercharger visits eliminates most BMS_a071 events entirely. If a coolant pump or sensor is failing and causing the pack to never reach charge temperature, expect $300 to $700 at an independent EV shop or up to $1,200 at a Tesla service center.