Hydraulic Pressure Unit
What it means
P0942 means the transmission control module has detected a problem with the hydraulic pressure unit — the pump and accumulator assembly that generates and holds the pressure the transmission needs to shift and operate. The engine still starts, but if the unit can't maintain pressure the transmission may shift harshly, slip, or struggle to engage gears. Low or contaminated fluid can contribute, so check the fluid before condemning the unit.
Can I keep driving? The engine starts, but if the hydraulic pressure unit can't maintain pressure the transmission may shift harshly, slip, or struggle to engage gears; get it checked promptly.
Real-world scan data
Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.
Common symptoms
What you'll notice
- Check-engine light on
- Harsh or abnormal shifting
- Slipping or difficulty engaging gears
- Reduced power or poor acceleration
Common causes
Most likely first
- Low or contaminated transmission fluidLikely
- Malfunctioning hydraulic pressure unit (pump/accumulator)Common
- Blocked or restricted hydraulic passagesCommon
- Wiring or electrical faults at the pressure unitLess often
- Failed transmission control module (TCM)Less often
How to diagnose & fix
Work through it in order
- Check the transmission fluid level and condition; top up if low and replace if contaminated.
- Inspect the pressure unit's wiring and connectors for damage or corrosion.
- Check for blocked or restricted hydraulic passages and clean or repair as needed.
- Test the hydraulic pressure unit with the proper tools and replace it if it can't hold pressure.
- If the unit and circuit are good, suspect the TCM. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0942?+
Can I just clear P0942?+
Related codes
Read & clear P0942 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.