P0900: Clutch A Actuator Control Circuit/Open
What to do
Expect the car either not to move or to take up sharply — the module cannot operate the clutch properly. Have it recovered rather than driven if it will not pull away cleanly. Ask whether the fault is in the circuit or in the actuator's ability to reach position, since those are very different jobs.
What this code means
A circuit fault in the actuator that operates the clutch on an automated manual or dual-clutch transmission. This is the electrical side of the mechanism whose control loop is described under P0805–P0811, and the division of labour between the two ranges is worth being clear about, because they are easy to conflate.
The P08xx codes are about outcomes: the clutch did not reach the position commanded, or it slipped when it should have held. These P09xx codes are about the wiring and drive — the circuit through which the module commands the actuator in the first place. A control error says the instruction was given and not carried out; a circuit fault says the instruction could not be given.
That distinction matters for cost. A circuit fault is a harness, a connector or a driver stage. A control error, once circuits are eliminated, points at the actuator or at the clutch itself, and those are inside the bellhousing.
Likely causes
Start here
- Damaged transmission wiring harness · moderate
- Corroded transmission connector · moderate
- Faulty clutch actuator · specialist
Less common
- Open circuit in actuator wiring · moderate
Rare
- Faulty transmission control module · specialist
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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