Actuator supply A is a high-side switch feeding several actuators together; its use differs by maker (Ford transmission solenoids, GM shared high-side driver, GM Europe 2.0 CDTI internal 5 V supply). P0659 means a short to voltage on the supply output, checked with the driver off – the output should then be dead (GM: 0.5 Ω or less to the supply, 20 of 25 samples; lamp after two trips in 2017–18, none in 2016). The driver can then no longer switch the actuators off; GM's transmission modules block their solenoid diagnostics while P0658/P0659 are active, and limp mode follows. On GM Europe's 2.0 CDTI it means the internal 5 V supply is too high, without MIL – the engine module is replaced.
Medium severity. Can I keep driving?If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
Symptoms
- Check engine light (GM from 2017)
- Transmission or actuator limp mode
- Actuators cannot be switched off
- Follow-up codes
Most likely causes
- Actuator supply wire shorted to battery or ignition voltage
- Harness chafed against a 12 V line
- Module (driver shorted; internal on the Saab diesel)
- External voltage fed back through a faulty actuator
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: hard
- It can trigger limp mode.
- It affects emissions.
What each character of P0659 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 6: Control modules and outputs
- 59: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0659?
If the car is running normally, drive in moderation to a repair shop. If it loses power or another warning appears, do not continue.
What causes code P0659?
The most common causes are: actuator supply wire shorted to battery or ignition voltage; harness chafed against a 12 V line; module (driver shorted; internal on the Saab diesel).
Related codes
- P0657Actuator Supply Voltage A Circuit/Open
- P0658Actuator Supply Voltage A Circuit Low
- P2671Actuator Supply Voltage B Circuit High
- P2669Actuator Supply Voltage B Circuit/Open
- P0643Sensor Reference Voltage A Circuit High
Sources
- law.cornell.edu: 13 CCR 1968.2
- gsi.ext.gm.com: 18OBDG03A Engine Diagnostics
- gsi.ext.gm.com: 17OBDG04 Engine Diagnostics
- gsi.ext.gm.com: 19OBDG03C Diagnostics
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.