P0943Generic code

P0943 Code: Hydraulic Pressure Unit Cycle Period Too Short

The P0943 code means the hydraulic pump of an automated manual transmission switches on too often, because the system loses pressure quickly. The gearbox shifts slowly and you can hear the pump working all the time. A worn accumulator is the usual cause.

Severity
Medium
Can I keep driving?
Yes, but with caution
Estimated cost
$150 to $800
Difficulty
Hard
System
Transmission
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0943 code means

Automated manual transmissions (Opel Easytronic, Fiat Dualogic, Toyota MMT, BMW SMG, Ford Durashift, Volkswagen ASG) and many dual-clutch gearboxes use electric or hydraulic actuators to release the clutch, pick the gear plane (selection) and engage the gear (engagement). The transmission computer watches every actuator through position sensors.

The pump charges an accumulator and then stops. If the accumulator loses pressure too fast, the pump has to start again right away. The computer measures that interval, and when it is too short it stores the P0943 code.

The most common cause is an accumulator that has lost its gas charge: it behaves like a tank with no reserve. An internal leak in a solenoid valve or in the actuator can do the same.

P0943 code symptoms

  • The hydraulic pump is heard running very often.
  • Slow shifts.

Likely causes of the P0943 code

  1. Accumulator with no gas charge. The most common cause.
  2. Internal leak in a solenoid valve. It lets pressure bleed back to the reservoir.
  3. Leak in the clutch actuator past the cylinder seal.

How to diagnose the P0943 code step by step

  1. Measure the time between pump activations.
  2. Test or replace the accumulator.

How to fix the P0943 code

  • Replace the accumulator.
  • Repair the internal leaks.

Once the repair is done, clear the P0943 code and listen to how often the pump runs.

Technical reference data

  • The accumulator is a wear item in these systems.
  • Reference values only: check the manufacturer data for your vehicle.

Brand-specific notes

These are the makes where this family of codes is most often seen. In many hydraulic systems the actuator fluid is a specific one, and the reservoir should be checked regularly.

P0943 on Opel

Very common on the Opel Easytronic.

P0943 on Fiat

Very common on the Fiat Dualogic.

P0943 on Toyota

Very common on the Toyota MMT.

P0943 on Smart

Very common on Smart cars fitted with this gearbox type.

P0943 on BMW

Very common on the BMW SMG.

Frequently asked questions about P0943

Can I drive with a P0943 code?
With caution. The gearbox shifts slowly and the pump works hard, so get it checked before the pump wears out.
What usually fails?
The accumulator. It loses its gas charge with age and can no longer hold pressure.
Is it expensive?
Moderately. An accumulator is not the most costly part in the system, but labor adds up.
How much does it cost to fix P0943?
Between $150 and $800, depending on whether it is the accumulator or an internal leak.
What does the P0943 code mean?
It means the pump is cycling on and off too quickly. The system is losing pressure faster than it should.

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