P0938 code meaning
Hydraulic Oil Temperature Sensor Range/Performance
Powertrain system Generic code P09xx codes Check engine light
What P0938 means
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.
P0938 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 2.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0938
- Gearbox warning light on
- Shift and clutch quality inconsistent with operating temperature
Common causes of P0938
- Most likelyTemperature sensor drifting or reacting sluggishly
- PossibleSignal lost through connector or wiring fault (as in Ferrari's no-signal case)
- Less likelyReal temperature anomaly from a cooler or thermostat fault
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hydraulic oil temp sensorWiring harnessTCM
What each part of P0938 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 9 | Area: transmission. |
| 38 | The exact fault in that area. |
What to do next
- Note P0938 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0938
What does P0938 mean?
P0938 means "Hydraulic Oil Temperature Sensor Range/Performance". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P0938?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0938 fail an emissions test?
Yes, it can. P0938 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0938 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. This is a job for a workshop.
Will P0938 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.