P0AE8

Code

Generic P — Powertrain

Hybrid/EV Battery Temperature Sensor D Circuit

Brand: Generic

Type: P — Powertrain

Views: UK: 20 EN: 29 RU: 25

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Page language: EN

Causes

Open or short in sensor D wiring (to ground or battery voltage)
Corroded, loose or damaged connector at sensor or BMS
Failed temperature sensor (thermistor)
Incorrect reference/pull-up voltage from BMS
Battery management module (BMS) input fault
Water ingress or mechanical damage to harness/connector

Symptoms

Battery/BMS warning lamp or hybrid system warning on dash
Reduced charge acceptance or disabled charging/regeneration
Reduced traction power or limp-home behavior
Incorrect pack temperature value on scan tool (erratic or out-of-range)
Possible stored related battery pack fault codes

What to check

Retrieve freeze-frame data and confirm P0AE8 active / permanent
Visual inspection of sensor D connector, wiring routing and harness for damage
Check for moisture, corrosion or pushed-out terminals at connectors
Backprobe sensor connector and measure reference voltage and signal with ignition on (BMS powered) using a multimeter
Measure sensor resistance at the sensor and compare to specification at known temperatures (ice, ambient, warm)
Check continuity and resistance between sensor harness pins and BMS pins (with HV system isolated as required)

Signal parameters

Sensor type: typically NTC thermistor (resistance decreases as temperature rises)
Typical signal voltage range: ~0.1–4.9 V depending on circuit design (verify OEM spec)
Typical resistance range at 25 °C: often in the low kilo-ohm range (example ~1–20 kΩ); verify OEM chart
Expected behaviour: steady, monotonic change in resistance/voltage as temperature is changed (no spikes or open-circuit readings)
Reference voltage: usually a stable 5 V or pull-up/pull-down supplied by BMS — verify presence

Diagnostic algorithm

SAFETY FIRST: Only qualified technicians should service high-voltage battery components. Follow manufacturer lockout/isolation procedures and use HV PPE before touching pack connectors or wiring.
Connect a diagnostic scanner, record all battery-related DTCs and live data for sensor D (pack temperature value and raw voltage/resistance if available). Note freeze-frame conditions.
Perform a visual inspection of sensor D connector and harness for damage, corrosion, heat damage, or water ingress. Repair physical damage before electrical testing.
With the vehicle in a safe state for low-voltage testing (follow OEM safety steps), backprobe the sensor D connector. Verify reference voltage/pull-up is present at the correct pin with ignition/BMS awake.
Measure sensor signal voltage at connector. If voltage is open/near battery or near 0 V, suspect open or short. If voltage noisy or intermittent, wiggle wiring to reproduce.
Remove sensor (if accessible) and measure resistance across sensor terminals at known temperatures (ambient, ice bath, warm water). Compare to OEM resistance vs temperature chart. If out of spec, replace sensor.
If sensor resistance is correct but signal at BMS is incorrect, check continuity and for short circuits between the sensor leads and battery + or chassis ground. Repair/replace damaged wiring or connector pins.
Inspect and test ground connections and BMS input circuitry. If wiring checks good and new sensor behaves same, consider BMS input/module fault and consult OEM procedures for module testing or replacement.
After repairs, clear codes, re-check live data and perform a functional test/drive. Confirm P0AE8 does not return and that battery temperature readings and charging/regeneration behaviors are normal.