The clutch actuator is a transmission part that allows the TCM to be able to manually engage and disengage the clutch without the use of a clutch pedal. This allows a manual transmission to essentially behave like an automatic transmission. But if there is a high-voltage signal detected on the clutch actuator circuit, a P0903 DTC will be saved.
How Serious is the Code?
The semi automatic transmission offers all of the benefits of a manual transmission, combined with all of the convenience of an automatic. However, if the TCM cannot engage and disengage the clutch, a number of serious drivability issues can occur. So yes, a P0903 diagnostic trouble code is quite serious.
Symptoms of a P0903 include:
- Engine won’t start
- Engine stalls when you stop
- Transmission refuses to change gears
- Limp Mode
- Failing clutch actuator
- Defective solenoid
- Clutch stroke/movement sensors have failed
- Damaged wiring and/or connectors
- Bad control module ground
- A fuse or fusible link has failed
- Clutch master cylinder has failed
- ECU programming issues
- Faulty ECU or TCM
How to Diagnose the Code?
Given the fact that each manufacturer’s transmission/clutch designs are completely unique, diagnosing a P0903 OBDII trouble code will require an understanding of the OEM diagnostic and troubleshooting procedures. But for the most part, involves checking the clutch actuator assembly, wiring, clutch master cylinder, and any associated solenoids, sensors and control modules.
What Repairs Will Fix P0903?
- 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
- P0900 – Clutch Actuator Circuit/Open
- P0901 – Clutch Actuator Circuit Range/Performance
- P0902 – Clutch Actuator Circuit Low