C0093: 4WD/AWD Power Transfer Unit Temperature Sensor

What it means

The control module monitors the temperature sensor on the 4WD/AWD power transfer unit. It sets this code when the sensor signal is missing or outside the expected range.

At a glance

• Usually lights the ABS or stability-control warning light
• The engine or gearbox may go into limp mode

How it works

The temperature sensor on the 4WD/AWD power transfer unit reports how hot the unit is to the control module. C0093 is set when that signal is missing or outside its expected range, which can indicate a sensor or circuit fault or an actually overheating transfer unit.

Common causes

Most likely first.

1. Temperature sensor failure
2. Damaged wiring or connector
3. Poor electrical connection or ground
4. Power transfer unit overheating

Symptoms

• ABS warning light on
• ESC/stability control deactivated
• Possible reduced brake assist
• Speedometer may behave erratically

How to diagnose it

1. Read ABS and driveline-module codes and freeze-frame data, and note whether the transfer unit was under load or hot when the fault appeared.
2. Inspect the transfer-unit temperature sensor and connector for damage, corrosion, fluid contamination, or a loose fit.
3. Check the sensor's wiring, power, ground, and signal path for opens, shorts, and poor connections using the wiring diagram.
4. Compare scan-tool temperature data with ambient conditions when the vehicle is cold, then watch whether the reading changes plausibly as the unit warms.
5. If the circuit checks out, investigate transfer-unit fluid condition and signs of overheating, and test the sensor against the manufacturer's specification.

Common fixes

• Repair damaged wiring or clean and secure the temperature-sensor connector.
• Correct a poor sensor ground or power connection.
• Replace a failed transfer-unit temperature sensor after confirming circuit integrity.
• Address a genuine overheating cause, such as an identified fluid or mechanical problem, before continued 4WD/AWD use.

Can I keep driving?

The control module may disable stability features or limit 4WD/AWD, and a genuinely overheating transfer unit can suffer further damage. Avoid heavy load and prolonged 4WD/AWD use; stop and let it cool if there are signs of overheating or unusual driveline noise.