P0EF4: Drive Motor C Temperature Sensor Circuit Low

What it means

The drive motor C temperature sensor circuit signal is below the expected threshold. The code does not by itself identify the cause.

At a glance

• Usually lights the check-engine light
• The engine or gearbox may go into limp mode

How it works

The Drive Motor C temperature sensor circuit provides a signal to the motor controls. This code sets when that signal is lower than the expected threshold, which can result from a short to ground or another fault; the code alone does not prove the sensor itself is at fault.

Common causes

Most likely first.

1. Signal wire shorted to ground
2. Internal sensor short
3. Connector pins corroded - high contact resistance

Symptoms

• EV/hybrid system warning light on
• Reduced motor power or torque
• Possible limp mode or vehicle shutdown

How to diagnose it

1. Check freeze-frame and live data to see whether Drive Motor C temperature is implausibly low or fixed at a limit.
2. With the high-voltage system safely disabled, inspect the sensor connector and harness for chafing, pinched insulation, corrosion, or a signal wire contacting ground.
3. Use the manufacturer's wiring diagram to test the signal wire for a short to ground and check connector terminals for damage or poor contact.
4. Test the Drive Motor C temperature sensor separately from the harness according to the manufacturer's specifications.
5. If the sensor circuit tests correctly, check the control-module input and ground reference for a fault.

Common fixes

• Repair a signal wire shorted to ground.
• Clean or replace corroded connector terminals.
• Replace the Drive Motor C temperature sensor if it tests shorted.
• Repair a faulty control-module input if wiring and sensor tests pass.

Can I keep driving?

Keep loads low and stop if a motor temperature warning or major power reduction occurs. The low signal may cause protective limits and may not reflect Drive Motor C's actual temperature.