B2247

Code

Other B — Body

EV Battery Pack Temperature Fault

Brand: Other

Type: B — Body

Views: UK: 26 EN: 40 RU: 21

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Page language: EN

Causes

Open or shorted battery pack temperature sensor (thermistor/NTC/PTC)
Damaged wiring harness, corroded or loose connector at the sensor or BMS
Faulty Battery Management System / battery pack control module
Intermittent connection (water ingress, broken wire, chafing)
Pack cooling/heating system failure causing real over-temperature
Incorrect replacement sensor or improper sensor installation

Symptoms

Reduced performance or reduced charge/discharge capability
Charging inhibited or fault light on dash (EV/Ready/Service EV)
HV battery pack cooling/heater running constantly or not at all
Vehicle enters limited power or limp mode
Possible smell or signs of overheating at battery pack (rare)

What to check

Read DTCs and freeze frame data with a manufacturer-capable scan tool; record all related battery/BMS codes
Check live data for battery pack temperature sensors and compare sensors (values should be consistent across modules)
Inspect wiring harness and connectors for damage, corrosion, moisture, or loose pins
Measure sensor resistance and/or voltage at the sensor and at the BMS connector (with pack de-energized as required)
Verify battery pack coolant temperature, coolant level, and thermistor locations if liquid-cooled
Check for other BMS or high-voltage system trouble codes (U-codes/P-codes) that may indicate related faults

Signal parameters

Thermistor type: NTC resistance typically decreases with increasing temperature (spec depends on manufacturer)
Common signal voltage range: 0–5 V (many systems use 1–4.5 V at normal temps); check OEM spec
Typical resistance examples (approx): ~100 kΩ at -40°C to a few kΩ at 25°C depending on sensor type — consult OEM chart
Fault threshold examples: out-of-range low or high voltage, open-circuit, short-to-ground, short-to-Vb (detectable by BMS)
Scan-tool live data: temperature values should be coherent (no sudden jumps or implausible values like -40°C or +125°C)

Diagnostic algorithm

Safety first: follow manufacturer HV isolation/disconnection procedures before touching pack wiring or sensors.
Retrieve and record all DTCs, freeze frame and BMS data with a capable scan tool; note which sensor(s) are reporting fault and measured temperatures.
Visually inspect battery pack exterior, sensor harness routing, connectors, and cooling lines for physical damage, contamination, or loose connectors.
With the pack in the safe/service state per OEM procedure, backprobe the sensor connector and measure resistance or signal voltage at ambient temp. Compare readings to OEM specifications or between sensors.
Wiggle test harness and connectors while monitoring live data to reproduce intermittent faults.
If an open/short is indicated, isolate and repair wiring (pin repair, replace connector, secure harness). Re-measure after repair.
If sensor readings at connector are good but BMS still reports fault, test voltage and continuity to the BMS input. If wiring is good, suspect BMS input circuitry and consult manufacturer guidance.
If actual pack over-temperature is suspected (high temperature confirmed on multiple sensors), inspect/diagnose pack cooling/heater system: coolant level, pump operation, fans, valves, and thermostats.
Replace the faulty temperature sensor(s) only with OEM-specified parts and reassemble per torque/positioning requirements.
Clear codes, perform system relearn if required, and monitor live data during controlled charge/discharge cycles to confirm the fault does not return.
If DTC persists after sensors and wiring verified/replaced, escalate to high-voltage battery service center or follow manufacturer BMS diagnostics; replacement of BMS or battery pack assembly may be required.