Hydraulic Oil Temperature Sensor Range/Performance
What it means
P0938 means the hydraulic (transmission) oil temperature sensor is reading outside its expected range or not tracking temperature the way the controller expects. The controller uses fluid temperature to fine-tune shift timing and to protect the transmission from overheating, so a drifting sensor can slightly change how shifts feel. The engine starts and drives normally; this is usually a sensor or wiring issue, but it's worth confirming the fluid isn't actually running hot.
Can I keep driving? Usually driveable; the transmission may not adapt shift timing correctly, so fix it at your convenience and confirm it isn't genuinely overheating.
Common symptoms
What you'll notice
- Check-engine light on
- Inaccurate hydraulic/transmission oil temperature reading
- Slightly altered shift timing or feel
Common causes
Most likely first
- Failing hydraulic oil temperature sensor drifting out of rangeLikely
- Wiring or connector problem in the sensor circuitCommon
- Actual fluid overheating being reported (verify before condemning the sensor)Common
- Faulty control module (less common)Less often
How to diagnose & fix
Work through it in order
- Compare the sensor's temperature reading to the actual fluid temperature.
- Inspect the sensor wiring and connector for damage or corrosion.
- Replace the temperature sensor if its reading is implausible or out of range.
- Confirm the transmission isn't genuinely running hot.
- Clear the code and retest.
FAQ
Quick answers
Is it safe to drive with P0938?+
Can I just clear P0938?+
Related codes
Often seen with P0938
Read & clear P0938 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.