Low or contaminated hydraulic fluid, often due to a leak or overdue service; Faulty hydraulic pressure sensor or its wiring connector; Failed hydraulic pressure control solenoid or actuator inside the unit; Internal mechanical wear or blockage in the hydraulic pressure unit; Damaged or corroded electrical harness at the unit; A restricted hydraulic filter or pickup screen; PCM software calibration issue or internal driver fault (less common)

DTC codes / P09xx · Transmission / P0942

P0942Hydraulic Pressure Unit

Q: What does code P0942 mean?

Hydraulic Pressure Unit. P0942 indicates that the powertrain control module (PCM) has detected a fault within the hydraulic pressure unit, which is the electro-hydraulic assembly responsible for generating and regulating pressure for the transmission or another hydraulically controlled system. The computer monitors the unit's pressure sensor and control circuit and sets this code when the measured pressure or electrical feedback falls outside the expected range for the commanded state.

P0942 indicates that the powertrain control module (PCM) has detected a fault within the hydraulic pressure unit, which is the electro-hydraulic assembly responsible for generating and regulating pressure for the transmission or another hydraulically controlled system. The computer monitors the unit's pressure sensor and control circuit and sets this code when the measured pressure or electrical feedback falls outside the expected range for the commanded state.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaTransmission

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Harsh or delayed transmission shifts, or the transmission entering limp mode
Slipping or flaring during gear changes under load
A whining or buzzing noise from the hydraulic pressure unit area
Reduced vehicle performance or inability to engage certain gears
In some cases, the vehicle may refuse to move or may stall when load is applied

Common causes, most likely first

Low or contaminated hydraulic fluid, often due to a leak or overdue service
Faulty hydraulic pressure sensor or its wiring connector
Failed hydraulic pressure control solenoid or actuator inside the unit
Internal mechanical wear or blockage in the hydraulic pressure unit
Damaged or corroded electrical harness at the unit
A restricted hydraulic filter or pickup screen
PCM software calibration issue or internal driver fault (less common)

How to diagnose and fix it

Check the hydraulic fluid level and condition; top off or replace fluid as needed
Inspect the wiring and connectors at the hydraulic pressure unit for damage or corrosion
Scan live data for commanded versus actual hydraulic pressure to confirm the fault
Test the hydraulic pressure sensor and control solenoid with a multimeter or scan tool
Perform a resistance and voltage drop test on the control circuit
Replace the faulty sensor, solenoid, or the hydraulic pressure unit if internal failure is confirmed
Clear codes and perform a relearn or adaptation drive cycle, then verify the repair

What the hydraulic pressure unit code hides

A low fluid level from a slow leak is the most common cause, yet many technicians replace the pressure unit before checking the fluid.
The code can be set by a simple loose or corroded connector at the unit, so always inspect the harness before condemning the unit.
On some vehicles, a failing transmission control module or a software calibration issue can mimic a hydraulic pressure unit fault.
The hydraulic pressure unit may also supply pressure for other systems such as power steering or brake assist, so related codes can appear.
A generic P0942 does not pinpoint the exact failed component; live data and circuit tests are required to avoid misdiagnosis.

Can I keep driving with P0942?

It is generally safe to drive a short distance to a repair shop if the vehicle shifts normally and the warning light is the only symptom, but avoid heavy loads or aggressive driving. If the transmission slips, shifts harshly, or the vehicle enters limp mode, stop driving and have it towed to prevent further damage.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.