P0943 code meaning
Hydraulic Pressure Unit Cycling Period Too Short
Powertrain system Generic code P09xx codes Check engine light
What P0943 means
In a hydraulic pressure unit the pump charges an accumulator up to a cut-out pressure and switches off until pressure falls to the cut-in point. By J2012 wording this code means the pump switches on again too soon, so the interval between charging cycles is shorter than expected. Typical reasons are internal leakage across valves or seals, or an accumulator that has lost its gas precharge and stores too little oil. Audi patents describe such accumulator and leakage checks based on charging switch-over times and pressure decay. No manufacturer documents this exact meaning publicly; Ferrari uses P0943 on its DCT for a system pressure command signal that is too high. CARB requires functional checks of transmission outputs. P0942 is the general fault, P0944 the loss of pressure.
P0943 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1.5 to 6 hours
- Clears after repairAfter a drive cycle
Symptoms of P0943
- Pump can be heard switching on unusually often
- Warning light on
- Slower or harsher gear changes
Common causes of P0943
- Most likelyAccumulator has lost its gas precharge
- Most likelyInternal leakage at valves, seals or actuator cylinders
- PossibleFaulty pressure switch or pressure sensor giving wrong cut-in point
- Less likelyLow or aerated hydraulic fluid
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hydraulic pressure unitTCM
What each part of P0943 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. |
| 43 | The exact fault in that area. |
What to do next
- Note P0943 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 P0943
What does P0943 mean?
P0943 means "Hydraulic Pressure Unit Cycling Period Too Short". In a hydraulic pressure unit the pump charges an accumulator up to a cut-out pressure and switches off until pressure falls to the cut-in point. It is a generic code, so it means the same on every make.
Is it safe to drive with P0943?
Drive gently and only to a workshop. With P0943 the car can go into limp mode (reduced power) to protect itself.
Will P0943 fail an emissions test?
Yes, it can. P0943 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 P0943 to fix?
Difficulty: hard. A typical repair takes 1.5 to 6 hours of work. This is a job for a workshop.
Will P0943 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.