P0946
Hydraulic Pump Relay/Control Circuit Range/Performance
Transmission
Generic OBD-II
High
What it means
P0946 means the hydraulic pump relay control circuit isn't performing within its expected range. On transmissions that use an electric hydraulic pump, that pump supplies the pressure needed to shift or engage the clutch, so a fault here can cause poor or failed shifting. The engine still starts, but the transmission may lose pressure. It usually points to a bad relay, wiring, or an unstable power supply.
High
Can I keep driving? Risky — if the hydraulic pump loses pressure the transmission or clutch may fail to shift or engage; don't drive far until it's fixed.
Common symptoms
What you'll notice
- Check-engine light on
- Abnormal hydraulic pump operation (won't run, or runs when it shouldn't)
- Loss of hydraulic pressure — poor or failed shifting/clutch engagement
- Inconsistent transmission performance or limp mode
Common causes
Most likely first
- Faulty hydraulic pump relayLikely
- Damaged or corroded wiring/connectors in the relay control circuitCommon
- Poor supply voltage or unstable charging systemCommon
- Faulty control module driving the relayLess often
How to diagnose & fix
Work through it in order
- Inspect the hydraulic pump relay and socket; swap with a known-good identical relay to test.
- Check the relay control wiring and connectors for damage or corrosion.
- Verify battery voltage and charging-system output are stable and within spec.
- Confirm the module commands the relay correctly and the pump responds.
- Replace the relay if it fails testing; address the control module only if wiring and power check good. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0946?+
Not really — the hydraulic pump feeds the pressure the transmission needs to shift or engage the clutch, so losing it can leave you stuck. Have it fixed before driving far.
Can I just clear P0946?+
It returns until the relay, its control circuit, or the power-supply problem is repaired.
Related codes
Often seen with P0946
Read & clear P0946 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