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.
How the engine computer detects it
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.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Pump can be heard switching on unusually often
- Warning light on
- Slower or harsher gear changes
Common causes
- Accumulator has lost its gas precharge Most likely
- Internal leakage at valves, seals or actuator cylinders Most likely
- Faulty pressure switch or pressure sensor giving wrong cut-in point Possible
- Low or aerated hydraulic fluid Less likely
How to diagnose P0943
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: hydraulic pressure unit, tcm.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Reading the code
- P
- Powertrain
- 0
- Generic (SAE) code
- 9
- Transmission
- 43
- Specific fault
Questions drivers ask
Can I drive with code P0943?
Drive gently and only as far as you need to. The engine computer may limit power to protect the engine, so avoid highways and heavy traffic until it's fixed. If the check engine light starts flashing, pull over.
Will my car pass an emissions inspection with P0943?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
Will P0943 clear by itself?
The light can go off after several drive cycles without the fault, but the code returns if the cause is still there. After a repair, the readiness monitors need a full drive cycle before an inspection.
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.