P0979: Shift Solenoid “C” Control Circuit Low OBD-II Trouble Code

The ECU controls shift solenoids by sending an electrical current through a coil of wire that is wrapped around the plunger mechanism inside the solenoid. If the computer detects an unusually low voltage situation somewhere along the shift solenoid C control circuit, it will store a P0979 DTC.

Need a replacement transmission? Get an estimate for replacement transmissions and local installation. Look up your transmission model by vehicle make and model.

What Transmission Do I Have?

How Serious is the Code?

The P0979 diagnostic trouble code gets triggered when the ECU is having problems controlling the C (a.k.a. number three) shift solenoid. The transmission problems related to this OBDII code may not be very severe at first. But they will continue to get worse, and eventually render a nonworking transmission.

Symptoms

Symptoms of a P0979 include:

  • Unusually harsh
  • Transmission may not shift into gear

Causes

  • Low transmission fluid level
  • Dirty transmission fluid/filter
  • Corroded/broken connectors and/or damaged wiring
  • The shift solenoid has malfunctioned

How to Diagnose the Code?

Diagnosing a P0979 OBDII code should begin with a check of the transmission fluid. If it’s dirty or low, this OBD2 code will be triggered. Damage wiring or broken/corroded connectors can also cause problems with a solenoid. If none of these issues are present, then the shift solenoid C itself will need to be tested.

Need a replacement transmission? Get an estimate for replacement transmissions and local installation. Look up your transmission model by vehicle make and model.

What Transmission Do I Have?

What Repairs Will Fix P0979?

  • Service the transmission
  • Replace or repair damage wiring/connectors
  • Replace shift solenoid

Related Codes

  • P0978 – Shift Solenoid “C” Control Circuit Range/Performance
  • P0980 – Shift Solenoid “C” Control Circuit High