What it means
The auxiliary transmission fluid pump control module detects that its internal temperature sensor signal is outside the expected range or does not respond as expected.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The auxiliary transmission-fluid pump control module uses an internal temperature sensor to track its own heat. P0C1D sets when the sensor signal is outside the expected range or changes in a way the module considers implausible, which differs from a circuit fault that simply indicates a general sensor-circuit problem.
Common causes
Most likely first.
- Faulty internal temperature sensor
- Poor sensor connection or wiring fault
- Faulty pump control module
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
How to diagnose it
- Record freeze-frame data and compare live module temperature with ambient and other available temperatures to see whether the reading is implausible or changes unexpectedly.
- Check related pump-module and transmission codes for evidence of overheating, poor fluid circulation, or electrical faults.
- Inspect the module connector and temperature-sensor wiring for corrosion, loose pins, chafing, heat damage, or intermittent contact.
- Test the sensor circuit and signal response across the manufacturer’s specified conditions to distinguish a drifting sensor from a wiring fault.
- If wiring and sensor response meet specification, test the pump control module and confirm the fault after repair.
Common fixes
- Repair a loose, corroded, or damaged temperature-sensor connection.
- Repair wiring that causes an intermittent or out-of-range signal.
- Replace the internal temperature sensor if its response is outside the manufacturer’s specification.
- Replace the pump control module if it reports an incorrect temperature despite a sound sensor circuit.
Can I keep driving?
Avoid long or demanding trips if shifting is abnormal, since the transmission may enter limp mode or suffer from inadequate fluid circulation. Stop safely if shifts slip, disappear, or become severely harsh.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.