P0946 code meaning
Hydraulic Pump Relay/Control Circuit Range/Performance
Powertrain system Generic code P09xx codes Check engine light
What P0946 means
The pump control circuit is electrically intact, but its behaviour does not match the command, for example a pump that keeps running after being switched off, or one that switches but is not followed by the expected feedback. No manufacturer documents this exact code publicly. In the hydraulic unit of an automated gearbox, as shown in a ZF patent, the pump only has to run until the accumulator is charged; a relay that sticks or switches late upsets that cycle. CARB requires functional checks on transmission outputs. P0945 is the general circuit or open fault, P0947 and P0948 the low and high faults, P094B a pump stuck on regardless of the relay. A pump that never stops drains the battery and wears quickly.
P0946 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0946
- Pump keeps running after switch-off
- Warning light on
- Auto stop-start not available
- Battery discharged after parking
Common causes of P0946
- Most likelyRelay contacts welded or sticking
- PossiblePump supply or control wire shorted to battery voltage
- Less likelyFaulty pump state feedback or control module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hydraulic pump relayWiring harnessTCM
What each part of P0946 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 9 | Area: transmission. |
| 46 | The exact fault in that area. |
What to do next
- Note P0946 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0946
What does P0946 mean?
P0946 means "Hydraulic Pump Relay/Control Circuit Range/Performance". The pump control circuit is electrically intact, but its behaviour does not match the command, for example a pump that keeps running after being switched off, or one that switches but is not followed by the expected feedback. It is a generic code, so it means the same on every make.
Is it safe to drive with P0946?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0946 fail an emissions test?
Yes, it can. P0946 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0946 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0946 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.