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DTC codes / P2Bxx · Hybrid propulsion / P2B25

P2B25Hybrid/EV Electronics Coolant Temperature Sensor C Range/Performance

P2B25 indicates that the hybrid or electric vehicle's electronics coolant temperature sensor C is reporting a range or performance problem, meaning the signal is outside the expected voltage or resistance window for the measured temperature. The computer compares this sensor's output against other temperature sensors and operating conditions, and it has detected an implausible or erratic reading that does not match the model.

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

Symptoms you may notice

  • Illumination of the check engine light or service vehicle soon message, often with no other noticeable symptoms.
  • Reduced hybrid system power or a forced limp mode if the coolant temperature is deemed unsafe.
  • Inconsistent or disabled cabin climate control, as the system may default to a safe mode.
  • Active grille shutters or cooling fans running continuously or not at all.
  • A message on the dash indicating hybrid system overheating or service required.
  • In rare cases, the vehicle may refuse to start or shift into gear if the coolant temperature is critical.

Common causes, most likely first

  1. Faulty electronics coolant temperature sensor C itself, due to internal failure or contamination.
  2. Damaged or corroded wiring or connector at the sensor, causing high resistance or intermittent signal.
  3. Coolant level low or air pockets in the electronics cooling loop, leading to erratic temperature readings.
  4. A stuck or failing thermostat in the electronics cooling circuit, causing abnormal temperature behavior.
  5. Debris or sludge buildup on the sensor tip, insulating it from the coolant and skewing the reading.
  6. A problem with the coolant pump or flow control valve reducing circulation and causing sensor performance issues.
  7. Rarely, a fault in the control module's sensor reference voltage or internal processing circuit.

How to diagnose and fix it

  1. Verify the coolant level in the electronics reservoir and inspect for leaks or air pockets; top up and bleed the system if needed.
  2. Visually inspect the sensor C connector and wiring for corrosion, chafing, or loose pins, and repair as necessary.
  3. Use a scan tool to read live data for sensor C and compare it with other temperature sensors during a cold start and warm-up to confirm the fault.
  4. Perform a resistance or voltage check on the sensor according to the manufacturer's specification, and replace the sensor if it is out of range.
  5. Check the electronics coolant pump and thermostat operation, including commanded versus actual flow, and repair any faults found.
  6. Clear the diagnostic trouble codes and perform a road test to verify the repair, ensuring the code does not return.
  7. If the code persists after sensor and circuit checks, follow the manufacturer's diagnostic flow for the control module and related systems.

Sensor C performance traps to avoid

  • A common misdiagnosis is replacing sensor C when the real problem is low coolant or air in the electronics cooling loop, which skews the temperature reading without any sensor fault.
  • The code can be set by a failing electronics coolant pump that causes temperature fluctuations, so always check pump operation before condemning the sensor.
  • In some vehicles, sensor C is part of a combined sensor cluster, and a fault in one sensor can affect the readings of others, leading to misleading live data.
  • Intermittent wiring faults often set P2B25 only under specific conditions such as vibration or temperature extremes, so a wiggle test on the harness is essential.
  • The code does not always mean the sensor is bad; a stuck thermostat or restricted coolant flow can cause the sensor to report a range/performance error even when the sensor itself is accurate.

Can I keep driving with P2B25?

It is generally safe to drive short distances to a repair shop, but avoid heavy acceleration, prolonged idling, or towing until the fault is repaired. If the vehicle enters limp mode or shows overheating warnings, stop driving and seek professional assistance to prevent damage to the hybrid electronics.

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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