By J2012 wording the hydraulic oil temperature reading is electrically valid but implausible, for example frozen, rising too slowly after a cold start or disagreeing with other temperature values. Ferrari uses P0938 on its DCT for the radiator outlet and gearbox inlet oil temperature sensor, but describes it in its bulletin as no signal, an electrical fault rather than a plausibility check; the code is read in the NCR gearbox ECU. CARB asks for rationality checks on temperature inputs. P0937 is the general circuit fault, P0939 and P0940 the low and high faults, P0941 intermittent. A wrong temperature value leads to poorly matched clutch and shift pressures and may limit the cooling strategy.
High severity. Can I keep driving?If the red oil warning light comes on, stop the car in a safe place and turn off the engine. Do not continue until you have confirmed the level and pressure.
Symptoms
- Gearbox warning light on
- Shift and clutch quality inconsistent with operating temperature
Most likely causes
- Temperature sensor drifting or reacting sluggishly
- Signal lost through connector or wiring fault (as in Ferrari's no-signal case)
- Real temperature anomaly from a cooler or thermostat fault
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It affects emissions.
What each character of P0938 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 9: Transmission
- 38: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0938?
If the red oil warning light comes on, stop the car in a safe place and turn off the engine. Do not continue until you have confirmed the level and pressure.
What causes code P0938?
The most common causes are: temperature sensor drifting or reacting sluggishly; signal lost through connector or wiring fault (as in Ferrari's no-signal case); real temperature anomaly from a cooler or thermostat fault.
Related codes
- P0937Hydraulic Oil Temperature Sensor Circuit
- P0939Hydraulic Oil Temperature Sensor Circuit Low
- P0940Hydraulic Oil Temperature Sensor Circuit High
- P0941Hydraulic Oil Temperature Sensor Circuit Intermittent
- P0711Transmission Fluid Temperature Sensor A Circuit Range/Performance
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.