On vehicles equipped with a semi-automatic transmission (sometimes referred to as a dual clutch transmission), the clutch actuator circuit allows the ECU to engage the clutch(s) so a gear change can occur, or the engine can be started. A P0900 DTC indicates that there is a voltage irregularity along this circuit.
How Serious is the Code?
Automated manual transmissions are usually pretty expensive to repair, so a P0900 diagnostic trouble code can be serious. The transmission problems associated with this OBD2 code can not only cause drivability problems, but they can also lead to expensive internal damage.
Symptoms of a P0900 include:
- Engine fails to start
- Engine stalling
- Transmission gets stuck in a gear
- Limp mode
- Failed clutch actuator
- Failed solenoid
- Failed sensor
- Damaged wiring/connectors
- Loose ground for the control module
- Failed fuse or fusible link
- Failed clutch master cylinder
- ECU programming error
- Failed ECU or TCM
How to Diagnose the Code?
In order to determine what is causing a P0900 OBDII trouble code, it’s important to first check the manufacturer’s technical service bulletins for known causes, solutions and software updates. Next, all of the wiring, connectors, ground wires, fuses, relays and sensors along this circuit carefully inspected. After that, the clutch actuator itself will need to be tested, along with any actuators, solenoids and control modules. The clutch master cylinder may also need to be checked.
What Repairs Will Fix P0900?
- Replace transmission clutch actuator
- Replace solenoid(s)
- Replace sensor(s)
- Repair or replace wiring/connectors
- Replace failed fuses and/or fusible link
- Replace clutch master cylinder
- Update ECU programming
- Replace failed TCM/ECU