Hydraulic Oil Temperature Sensor Range/Performance
The P0938 code indicates that the Powertrain Control Module (PCM) has detected a signal from the hydraulic oil temperature sensor that is outside the expected range or not performing correctly. This sensor monitors the temperature of the hydraulic fluid in the transmission or clutch system. A faulty sensor, wiring issues, or low hydraulic fluid can cause this code. The PCM uses this data to adjust shift patterns and protect the transmission from overheating.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Transmission shifting issues (harsh or delayed shifts)
- Transmission overheating
- Reduced fuel economy
2. Most Common Causes
- Faulty or deteriorated hydraulic oil temperature sensor
- Damaged, corroded, or loose sensor wiring
- Short circuit or open circuit in the sensor harness
- Sensor connector contaminated with oil, dirt, or corrosion
- Internal PCM failure (rare)
- Low hydraulic oil level or degraded oil condition
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Inspect the hydraulic oil temperature sensor and its wiring for damage or corrosion.
Step 3: Check hydraulic fluid level and condition; top off or replace if necessary.
Step 4: Test sensor resistance and compare to manufacturer specifications.
Step 5: If sensor and wiring are okay, check PCM for software updates or faults.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as it can lead to transmission overheating and damage. Have it diagnosed promptly.
How much does it cost to fix?▼
Typically $50-$150 for sensor replacement, plus diagnostic fees. Costs may vary based on vehicle and labor rates.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.