P2796
Electric/Auxiliary Transmission Fluid Pump A Control Circuit/Open
Transmission
Generic OBD-II
Medium
What it means
P2796 means the transmission controller detects an open in the control circuit for the auxiliary (electric) transmission fluid pump. That pump maintains line pressure when the engine is stopped, so it's key to auto stop-start and hybrid operation. The car still drives, but expect harsher engagements and disabled stop-start until the circuit or pump is repaired.
Medium
Can I keep driving? Usually yes — the car drives, but auto stop-start may be disabled and engagements can feel harsh; fix it to avoid extra clutch wear.
Common symptoms
What you'll notice
- Check-engine light on
- Auto stop-start disabled or restarts feel harsh
- Delayed or harsh engagement after the engine restarts
- Reduced shifting smoothness or (on hybrids) reduced EV operation
Common causes
Most likely first
- Open in the auxiliary pump control circuit wiring or connectorLikely
- Failed auxiliary transmission fluid pumpCommon
- Faulty pump relay or driverCommon
- Poor ground or corroded connection at the pumpLess often
- TCM output-driver fault (less common)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and inspect the aux-pump connector and wiring for opens or corrosion.
- Verify power and ground at the pump.
- Command the auxiliary pump with a scan tool if the function is supported.
- Repair the open circuit or replace the pump/relay if it fails testing.
- Clear the code and confirm stop-start/engagement operate normally.
FAQ
Quick answers
Is it safe to drive with P2796?+
Generally yes. The auxiliary pump keeps line pressure up when the engine is off, so its loss mostly affects auto stop-start smoothness rather than basic drivability.
Can I just clear P2796?+
It comes back until the open circuit or failed pump is repaired, since the controller re-checks the pump each drive.
Related codes
Often seen with P2796
Read & clear P2796 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX