Faulty electronics coolant temperature sensor C; Short to ground in the sensor signal circuit; Damaged or corroded sensor connector; Open or high-resistance ground circuit for the sensor; Low coolant level or air pockets in the electronics cooling system; Failed coolant pump or restricted coolant flow; Control module internal fault (rare)

DTC codes / P2Bxx · Hybrid propulsion / P2B26

P2B26Hybrid/EV Electronics Coolant Temperature Sensor C Circuit Low

P2B26 indicates that the hybrid or electric vehicle's electronics coolant temperature sensor C circuit is reporting a voltage below the normal range, which the control module interprets as an excessively low temperature or a short to ground. The computer sets this code when the signal voltage stays lower than the expected threshold for a calibrated time, often indicating a wiring fault, sensor failure, or coolant flow issue.

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
Reduced hybrid system power or forced limp mode
Coolant temperature gauge reading abnormally low or not moving
Possible overheating warning if the sensor is stuck low and the system cannot detect high temperatures
Often no symptoms besides the warning light

Common causes, most likely first

Faulty electronics coolant temperature sensor C
Short to ground in the sensor signal circuit
Damaged or corroded sensor connector
Open or high-resistance ground circuit for the sensor
Low coolant level or air pockets in the electronics cooling system
Failed coolant pump or restricted coolant flow
Control module internal fault (rare)

How to diagnose and fix it

Verify coolant level and condition; top off or bleed the system if low
Inspect the sensor and its connector for corrosion, damage, or loose pins
Measure sensor resistance and compare to manufacturer specifications
Check the signal circuit for a short to ground using a multimeter
Check the ground circuit for continuity and resistance
If wiring and sensor test good, diagnose the control module or consult a specialist
Clear codes and perform a road test to confirm the repair

Don't overlook coolant level and air pockets

A low coolant level or trapped air in the electronics cooling loop can cause the sensor to read cold even when the sensor and wiring are perfect.
The sensor C circuit often shares a ground with other sensors, so a bad ground can set multiple codes and mislead you into replacing the sensor.
A short to ground in the signal wire may be intermittent and only appear when the harness is moved or the vehicle is hot, so wiggle-test the harness during diagnosis.
This code does not always mean the sensor is bad; a failed coolant pump can prevent hot coolant from reaching the sensor, keeping its voltage low.
After repairs, the control module may need a relearn or adaptation reset before the code stays cleared.

Can I keep driving with P2B26?

You can drive short distances to a repair shop, but avoid heavy acceleration, long trips, or towing because the system may not detect overheating and could suffer damage. If the vehicle enters limp mode or shows a high-temperature warning, stop safely and seek professional assistance.

Tools that help

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