Error Code P0912 is defined as Gate Select Actuator Circuit Low. This is a generic trouble code, meaning it applies to all vehicles equipped with the OBD-II system, especially those made since 1996 up to the present. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.

Vehicles with Automated Manual Transmissions and Dual Clutch often use a system called Gear Shift Actuator Module (GSAM). The job of GSAM is to engage or disengage the clutch and choose the transmission gear based on the commands from the Transmission Control Module (TCM).

When this code appears, that means the powertrain control module (PCM) has determined a problem with the Gate Select Actuator Circuit. The code means the said circuit is running low.

Other related codes include:

  • Error Code P0910
  • Error Code P0911
  • Error Code P0913

Common Symptoms

  • Stalling while idling
  • Sluggish acceleration
  • Difficult shifting
  • Increase in fuel consumption

Possible Causes

This code is likely caused by faulty wiring, such as loose connection, frayed wirings. Other possible causes include:

  • Blown fuse
  • Faulty PCM (rare)

How to Check

You will need an advanced scanned, a specialized scanner, wiring diagram of the Control Area Network Bus, a digital volt/ohmmeter (DVOM), and an auxiliary ground cable.

First, check the connectors, wirings, and all related components. Look for signs of damage or faults. Replace damaged components as necessary, then clear the codes to see if the Error Code comes back.

If the code comes back, then proceed on checking the voltage and ground signal at the Gate Select Actuator circuit using the DVOM.

If there is no voltage or ground signal present, disconnect the PCM and related control modules to test for the Gate Select Actuator circuit’s continuity.

Next, check the pins of the CAN bus wiring harness using a specialized scanner. Also, refer to the CAN-BUS wiring diagram and compare the results to the manufacturer’s specifications. Use an auxiliary cable to help with the CAN Bus harness diagram check.

Next, check the PCM and Gate Select Actuator circuit switch and PCM for continuity. Then, test for continuity at the TCM as well. Next, check the continuity of the PCM and see if it has gone bad.

Clear the codes and retest to see if the problem comes back.

How to Fix

  • Replacement of faulty wiring, connectors, and related components
  • Replacement of damaged Gate Select Actuator circuit
  • Replacement of faulty Gate Select Actuator circuit switch
  • Replacement of blown fuses (determine the cause of the blown fuse to prevent the problem in the future)
  • Replacement of damaged or reprogramming of PCM or TCM (rare)

Since this code causes shifting problems, it should not be left untreated for a long time.

The most common misdiagnosis in this code is not checking the wiring thoroughly before replacing anything.