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Home / DTC / B2870 — Battery Temperature Sensor Circuit Malfunction

B2870 — Battery Temperature Sensor Circuit Malfunction

Detailed page for trouble code B2870.

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Code

B2870

Generic B — Body

Battery Temperature Sensor Circuit Malfunction

Brand: Generic
Type: B — Body
Views: UK: 2 EN: 5 RU: 5
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Page language: EN

Causes

  • Open or short in battery temperature sensor wiring or connector
  • Corroded, loose, or damaged sensor connector
  • Faulty battery temperature sensor (thermistor)
  • Poor ground or reference voltage to the sensor circuit
  • Failed module that reads the sensor
  • Intermittent wiring damage (chafe, pinched, rodent damage)

Symptoms

  • DTC B2870 stored and MIL may be illuminated (depending on OEM strategy)
  • Battery management/charging irregularities or warnings
  • Reduced charging performance or limp-home charging strategy
  • Inaccurate battery state-of-charge or range estimates
  • Possible intermittent charging system faults or unpredictable battery behavior

What to check

  • Read and record freeze frame and related codes with a scan tool
  • Visually inspect sensor, connector, and wiring for corrosion, damage, or moisture
  • Check battery and chassis grounds and associated fusing
  • Monitor live battery temperature sensor data with a scan tool while warming/cooling
  • Perform a wiggle test on wiring while watching live data for intermittent changes

Signal parameters

  • Sensor type: usually a thermistor (NTC/Pt) — resistance changes with temperature
  • Expected behavior: resistance decreases as temperature increases (NTC) or increases (PTC) depending on sensor type
  • Typical voltage range at module input: ~0.1 V (very cold/short) to ~4.9 V (very hot/open), exact values are manufacturer-dependent
  • Open-circuit indication: very high resistance (>>100 kΩ) or voltage near rail (depending on pull-up/pull-down)
  • Short-circuit indication: near 0 Ω or voltage near 0 V
  • Normal resistance/voltage at ambient: manufacturer-specific — consult spec for exact numbers

Diagnostic algorithm

  1. Connect a scan tool and confirm B2870; record freeze-frame data and any related codes (charging, battery management, communication faults).
  2. Perform a visual inspection of the battery temperature sensor, connector, and harness for corrosion, loose pins, burns, or mechanical damage.
  3. With connector disconnected, measure sensor resistance at a known ambient temperature and compare to manufacturer specification. If spec unknown, check for reasonable resistance (not open/infinite or short).
  4. Backprobe the sensor connector and monitor voltage/ohms at the module side while referencing ground and key-on as required. Verify reference voltage and ground are present and stable.
  5. Wiggle the harness and connector while observing live data and voltages to identify intermittent faults.
  6. If wiring and connector check good, replace the sensor and clear codes. Re-test and monitor live data to confirm proper operation as temperature changes (warm engine or use heat source/cold spray safely).
  7. If fault persists after sensor replacement, trace and test wiring continuity between sensor and module; repair any opens/shorts, then retest.
  8. If wiring and sensor are good, verify module software and communications; consider module diagnosis or reprogramming per OEM procedures.

Likely causes

  • Corroded or loose connector at the battery temperature sensor
  • Open or shorted wiring between sensor and control module
  • Failed battery temperature sensor
  • Poor ground or blown fuse affecting sensor reference
  • Software/module fault (less common)

Fault status

⚠️ Status
Battery Temperature Sensor Circuit Malfunction — check sensor, wiring, and connector
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B2871 B2880 P0112 P0113 U0121
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