Faulty auxiliary coolant temperature sensor A; Damaged or corroded wiring harness or connector at the sensor; Open or short circuit in the sensor signal or ground circuit; Coolant level low or air pockets causing the sensor to read incorrectly; Failed auxiliary coolant pump leading to stagnant coolant and abnormal temperature readings; PCM internal fault or software issue affecting the sensor circuit; Contamination or sludge on the sensor tip altering its response

DTC codes / P0Exx · Hybrid propulsion / P0E7C

P0E7CAuxiliary Cooling Coolant Temperature Sensor A Circuit Range/Performance

P0E7C indicates that the auxiliary cooling coolant temperature sensor A circuit is reporting a range or performance fault, meaning the powertrain control module (PCM) has detected a signal that falls outside the expected voltage or temperature range for the current operating conditions. The PCM compares the sensor's output against other temperature inputs and its own rationality models, and it sets this code when the signal is not plausible or is intermittent.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaHybrid propulsion

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Auxiliary cooling fan may run continuously or fail to activate when needed
Reduced cooling performance for the auxiliary system, such as the intercooler or battery pack cooling loop
Possible overheating warning or derating of auxiliary components in extreme conditions
Intermittent operation of the auxiliary coolant pump or fan
Sometimes a stored freeze-frame showing an abnormal sensor voltage

Common causes, most likely first

Faulty auxiliary coolant temperature sensor A
Damaged or corroded wiring harness or connector at the sensor
Open or short circuit in the sensor signal or ground circuit
Coolant level low or air pockets causing the sensor to read incorrectly
Failed auxiliary coolant pump leading to stagnant coolant and abnormal temperature readings
PCM internal fault or software issue affecting the sensor circuit
Contamination or sludge on the sensor tip altering its response

How to diagnose and fix it

Scan all modules and record freeze-frame data to confirm the code and check for related codes
Visually inspect the sensor, connector, and wiring for damage, corrosion, or loose pins
Measure sensor resistance and compare to the manufacturer's temperature-resistance chart
Check the signal voltage at the PCM while wiggling the harness to detect intermittent faults
Verify coolant level and bleed the auxiliary cooling system if air is suspected
Test the auxiliary coolant pump operation and flow to rule out stagnant coolant
Replace the sensor only after electrical and cooling system checks pass, then clear codes and verify repair

Auxiliary cooling sensor pitfalls to check first

A common misdiagnosis is replacing the sensor when the real problem is a chafed wire in the harness near the auxiliary radiator or fan shroud.
Low coolant or trapped air in the auxiliary loop can cause the sensor to report a range error even though the sensor itself is good.
The auxiliary cooling system often shares coolant with the main system, so a failed auxiliary pump can create temperature swings that set this code.
This code can be set by a momentary glitch during a cold start if the sensor heater circuit (if equipped) is weak, so check for repeat occurrences before replacing parts.
On some vehicles, the auxiliary coolant temperature sensor is used for battery thermal management, and a fault may cause reduced fast-charging performance without any dashboard warning.

Can I keep driving with P0E7C?

You can usually continue driving with this code, but avoid heavy loads or high ambient temperatures that demand auxiliary cooling, and address the fault promptly to prevent overheating of auxiliary components.

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.