P099C OBD-II: Shift Solenoid "G" Control Circuit High

P099C Severity

Urgent

Should you fix P099C yourself?

Identifying an OBD code is just the start of a complete diagnostic routine. Most trouble codes are caused by a sensor reporting a value that is out of range. Just replacing a sensor may not fix underlying issues. Be sure to understand the code, the part or system in your car that the code refers to, and the risks of delaying professional repair.

Proper diagnosis will save you time and money on unnecessary repairs.

Urgent codes indicate immediate action is necessary. These are urgent and significant malfunctions that can cause severe damage to the vehicle or harm the driver and passengers.

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What causes OBD-II fault code P099C?

The Transmission Fluid Pressure Solenoid allows the engine's control module (PCM) or Transmission Control Module (TCM) to use hydraulic fluid to engage the clutches in the transmission to allow for smoother shifting while driving. If the PCM or TCM detects an issue with the electrical circuit to or from this solenoid, the PCM or TCM will set code P099C.

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OBD II Fault Code

  • OBD II P099C

OBD-II Code Transmission may not shift properly is defined as a Shift Solenoid "G" Control Circuit High

The Transmission Fluid Pressure Solenoid allows the engine's control module (PCM) or Transmission Control Module (TCM) to use hydraulic fluid to engage the clutches in the transmission to allow for smoother shifting while driving. If the PCM or TCM detects an issue with the electrical circuit to or from this solenoid, the PCM or TCM will set code P099C.

Transmission may not shift properly Symptoms

  • Increased fuel consumption
  • Transmission may not shift properly

Common Problems That Trigger the P099C Code

  • Transmission Control Module (TCM) failure
  • Transmission fluid level is low
  • Transmission shift solenoid failure
  • Wiring issue
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