P2D46

Code

Generic P — Powertrain

Hybrid/EV Battery Pack B Over Temperature

Brand: Generic

Type: P — Powertrain

Views: UK: 21 EN: 28 RU: 20

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Page language: EN

Causes

Actual battery pack B temperature above safe threshold due to ambient heat or heavy load
Battery pack cooling system malfunction (coolant pump, valves, or refrigerant circuit)
Cooling fan(s) failure or obstructed airflow to the battery pack
Low or contaminated coolant level, clogged heater/cooler cores, or blocked cooling passages
Degraded or failing battery cells generating excess heat (internal cell fault or high internal resistance)
BMS sensor fault or inaccurate temperature sensor reading (open/shorted sensor, poor sensor ground)

Symptoms

Battery/EV warning lamp or thermal warning message on cluster
Reduced propulsion power or limp-home/derate mode
Charging disabled or charging paused due to over-temperature
Reduced range or sudden change in state-of-charge behavior
Cooling system fans/pump running continuously or unusually loud
Observed high temperature reading for pack B in live data or telematics

What to check

Read freeze frame and all related DTCs with OEM-capable scan tool; capture live data for pack B temperature
Compare pack B temperature sensor reading to pack A/C (other packs) and ambient temperature
Inspect battery cooling system: coolant level, hoses, connectors, pump operation, and fans for correct function
Visually inspect battery pack B area for physical damage, debris, or blocked air paths
Check wiring harness and connectors to pack B sensors and BMS for corrosion, damage or loose pins
Verify BMS reports, contactors, and any thermal management valve positions (if applicable)

Signal parameters

Pack B temperature (°C / °F) — observe trend and peak values
Ambient air temperature (°C / °F)
Coolant temperature in battery loop (°C / °F)
Cooling pump status and RPM or current draw
Cooling fan speeds and commanded duty cycle
BMS thermal protection status (derate/shutdown/charging inhibit flags)

Diagnostic algorithm

Retrieve all DTCs and freeze-frame data. Note pack B temperature at time of fault, ambient temp, and vehicle operating condition.
Reproduce condition, if safe: operate vehicle at similar load/charging scenario while monitoring live pack B temperature and thermal management parameters.
Inspect cooling system: verify coolant level, visually check hoses and connections, and run the coolant pump while watching flow/pressure and pump current draw.
Verify cooling fans operate under high-load or high-temp conditions and that airflow to the battery pack is not obstructed.
Compare pack B temperature to pack A (or other modules). If pack B reads significantly higher, suspect local issue (sensor, cooling circuit, or internal cell heat).
Check temperature sensor circuits for proper voltage, resistance, and grounding. Repair any open/shorts or poor connectors.
If sensor readings are inconsistent, substitute or bench-test the sensor per manufacturer procedure, or replace sensor and re-test.
Inspect battery pack internals (service manual required) for signs of cell swelling, leakage, or local heat — only trained personnel should open high-voltage components.
If cooling hardware is faulty (pump, fans, valves), repair or replace and confirm cooling restores normal temperature under comparable load.
If pack temperature remains high with functioning cooling, consider detailed cell-level testing and capacity analysis; consult manufacturer guidance for battery pack repair or replacement.
Clear codes and perform a drive/charge cycle to verify the fault does not return. Document all findings and any repairs.