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DTC codes / P0Axx · Hybrid propulsion / P0ACB

P0ACBHybrid/EV Battery Temperature Sensor C Circuit Range/Performance

P0ACB indicates that the hybrid or electric vehicle battery temperature sensor circuit C is reporting a range or performance fault, meaning the voltage or resistance signal from that sensor falls outside the expected window for the measured temperature. The battery energy control module compares the sensor C reading against other temperature sensors and operating conditions, and it sets this code when the signal is implausible, stuck, or inconsistent over time.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyProfessional
AreaHybrid propulsion

Symptoms you may notice

  • Illumination of the check engine light or hybrid system warning lamp, often with no other noticeable symptoms.
  • Reduced electric-only driving range or a forced switch to gasoline engine operation in a plug-in hybrid.
  • A message on the dash indicating the hybrid battery is too hot or too cold, even when ambient conditions are normal.
  • Intermittent loss of charging capability or a refusal to accept a full charge.
  • Power derating or limp-home mode when the control module cannot trust the battery temperature data.
  • In rare cases, a no-start condition if the battery management system disables the high-voltage contactors.

Common causes, most likely first

  1. A faulty battery temperature sensor C itself, with an open, shorted, or drifted thermistor element.
  2. Damaged or corroded wiring and connector pins between sensor C and the battery energy control module.
  3. High-resistance connections at the sensor harness splice or ground point causing a skewed voltage signal.
  4. A software calibration issue in the battery energy control module that misinterprets a valid sensor signal.
  5. Internal failure of the battery energy control module's sensor input circuit.
  6. Physical damage to the sensor or its harness from heat, vibration, or moisture intrusion inside the battery pack.
  7. A genuine battery pack overheating condition that pushes sensor C beyond its expected range, though this usually sets additional codes.

How to diagnose and fix it

  1. Connect a scan tool and record the freeze-frame data for P0ACB, then compare sensor C's temperature reading with sensors A, B, and D to see if it is an outlier.
  2. Visually inspect the sensor C harness, connector, and pins for chafing, corrosion, or loose terminals, and repair any obvious damage before replacing parts.
  3. Measure the resistance of sensor C at the connector and compare it to the manufacturer's temperature-resistance chart for the current ambient temperature.
  4. Back-probe the sensor C signal wire at the control module and check for a stable voltage that changes predictably when the sensor is warmed or cooled.
  5. Perform a wiggle test on the harness while watching live sensor C data to catch intermittent opens or shorts that do not appear at rest.
  6. If the sensor and wiring test good, check for technical service bulletins or software updates for the battery energy control module before condemning it.
  7. Replace the faulty sensor or control module only after confirming the fault follows the component, then clear the code and verify the repair with a road test and live data review.

What sensor C really tells you

  • Sensor C is often one of several thermistors inside the pack, and a single skewed sensor can make the whole pack appear to have a temperature problem when only that sensor is at fault.
  • A common misdiagnosis is replacing the battery pack when the real fault is a corroded connector pin or a chafed wire in the harness that runs along the pack casing.
  • The code can be set by a sensor that reads correctly at room temperature but drifts only when the pack is hot or cold, so a cold resistance check alone is not conclusive.
  • Some vehicles set P0ACB after a low-voltage event or a battery replacement if the control module's learned temperature offsets are not reset with a scan tool.
  • A failing 12-volt auxiliary battery can cause erratic sensor readings on the low-voltage side of the hybrid system, so always verify supply voltage and grounds before chasing the sensor.

Can I keep driving with P0ACB?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy acceleration, sustained high speeds, and fast charging because the control module may not be able to protect the battery pack without reliable temperature data. If the dash displays a high-voltage battery overheating warning or the vehicle enters limp mode, stop safely and have it towed.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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