P0942
Hydraulic Pressure UnitP0942 is a generic OBD-II powertrain diagnostic trouble code: Hydraulic Pressure Unit. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P0942 means
P0942 indicates that the PCM or TCM has detected a fault within the hydraulic pressure unit of the automatic transmission. The hydraulic pressure unit encompasses the transmission oil pump and its associated control circuitry — the system responsible for generating and maintaining the fluid pressure that powers all gear-engagement operations inside the transmission. Without adequate hydraulic pressure, clutch packs cannot clamp, bands cannot hold, and the transmission cannot transfer engine torque to the drivetrain reliably.
This code is relatively broad and may be set due to mechanical failure of the pump itself, an electrical fault in the pressure control circuit feeding the pump solenoid or regulator, or a severe fluid delivery problem (extremely low level, heavily contaminated fluid, or a blocked filter/cooler line) that prevents the pump from building sufficient pressure. Some manufacturers also use P0942 to flag a fault in the electro-hydraulic control unit on dual-clutch or continuously variable transmissions, where an electrically driven pump or pressure accumulator replaces the conventional mechanical oil pump.
The most visible symptom is typically transmission hesitation or complete refusal to shift, often accompanied by the vehicle entering limp mode — a fail-safe strategy that restricts the transmission to one forward gear to allow the vehicle to reach a workshop without causing catastrophic internal damage. In severe cases the transmission may disengage entirely, leaving the driver without drive or reverse. Continuing to operate the vehicle in this condition can cause irreversible damage to clutch packs, bearings, and the pump itself.
P0942 is associated predominantly with Chrysler, Jeep, and Volkswagen Group vehicles but can appear on any platform using this standardised code. A thorough diagnosis must include both a hydraulic line pressure test and an electrical inspection of the pump control circuit before condemning the pump assembly itself, as wiring faults and fluid issues are far cheaper to remedy.
Common causes
Most-frequently reported root causes when P0942 is logged.
-
1
Low transmission fluid level causing pump cavitation
-
2
Severely degraded or contaminated transmission fluid
-
3
Clogged transmission oil filter restricting pump suction
-
4
Failed or worn transmission oil pump
-
5
Stuck or faulty transmission pressure regulator valve
-
6
Blocked transmission cooler line reducing fluid return
-
7
Damaged wiring or connector at the hydraulic pressure unit control circuit
-
8
Faulty pressure control solenoid or valve body fault
-
9
PCM/TCM fault (rare, after mechanical and electrical checks pass)
Symptoms drivers notice
How to diagnose P0942
A typical diagnostic flow when this code is present.
-
1
Check transmission fluid level and condition immediately — low or burnt fluid is the most accessible cause
-
2
Replace the transmission filter if overdue or if fluid shows contamination
-
3
Scan for all transmission codes and freeze-frame data; companion codes may identify a specific solenoid or circuit
-
4
Inspect wiring, connectors, and grounds at the transmission control unit and hydraulic unit for damage or corrosion
-
5
Perform a hydraulic line pressure test at idle and stall to measure actual pump output and compare against manufacturer specification
-
6
Test pressure control solenoid operation with a scan tool — verify commanded vs. measured pressure correlation
-
7
If pump output is confirmed low and fluid/filter are good, inspect the pressure regulator valve for sticking
-
8
If all electrical and fluid checks pass, suspect internal pump wear — pump replacement or transmission overhaul may be required
Related powertrain codes
Frequently asked questions
Is it safe to drive with code P0942?
No. A hydraulic pressure unit fault means the transmission may not shift reliably and could lose drive entirely without warning. Limp mode may allow you to reach a workshop at low speed, but continued driving risks destroying the transmission internally.
Which vehicles most commonly get P0942?
P0942 is most frequently reported on Chrysler and Jeep platforms (45RFE, 545RFE, 66RFE) and Volkswagen/Audi DSG dual-clutch transmissions.
Can I fix P0942 by just changing the fluid and filter?
If low or contaminated fluid is the cause, a fluid and filter service may resolve the code. However, if the pump has already suffered damage from running low, a service alone will not be sufficient.
How much does it cost to repair P0942?
Costs range widely: a fluid and filter service costs around $100–$200. Pressure solenoid or valve body repairs typically run $200–$600. A transmission oil pump replacement or transmission overhaul can exceed $1,500–$3,500.
Could a PCM or TCM software issue cause P0942?
Rarely, but it is possible. Some manufacturers have issued software updates to revise pressure-fault detection thresholds.
Disabling P0942 in software
RaceTune can permanently disable P0942 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
Got P0942 in your scan?
Upload your ECU file — we'll identify the exact software version and confirm whether a disable is available for your car.
Upload your file