P0942 — Hydraulic Pressure Unit

What P0942 means

P0942 is the standardized powertrain DTC for “Hydraulic Pressure Unit.” The code identifies the monitored condition; it does not by itself prove which part failed.

Possible symptoms

• Delayed engagement
• Slipping or flare
• Harsh shifts
• Limp mode
• Transmission warning

Causes to test

These are diagnostic possibilities, not a statistical parts-replacement ranking. Vehicle-specific service information takes priority.

• Low fluid or aeration
• Pump or hydraulic pressure loss
• Valve-body/pressure-control fault
• Pressure sensor/switch circuit fault
• Internal leak or wear

Step-by-step diagnostic workflow

1. Verify fluid level/condition using the exact transmission procedure.
2. Compare pressure sensor data with commanded pressure and operating state.
3. Check sensor circuit/reference voltage if the code is electrical.
4. Perform manufacturer hydraulic pressure testing if slip/pressure faults persist.
5. Perform circuit or mechanical tests specified by service information; repair the confirmed root cause.
6. Clear codes only after repair, then complete an appropriate drive cycle and verify the code and symptoms do not return.

Scan data worth checking

• Transmission fluid pressure
• Pressure-control command
• Input/output speed
• Transmission fluid temperature
• Commanded gear

Severity and drivability

High if the transmission is slipping, delayed, or overheating. Low pressure can quickly damage friction components.

Stop driving and investigate immediately if there is a flashing MIL, oil-pressure warning, overheating, fuel leakage, severe misfire, major loss of power, abnormal mechanical noise, or a transmission that is slipping badly.

Common diagnostic mistakes

• Continuing to drive a slipping transmission
• Assuming a low-pressure DTC is only a sensor problem
• Using universal pressure specifications

Related generic codes