Chassis, generic

C0621 Variable Effort Steering Lock/Safety Actuator Control Circuit Low

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

C0621 reports the lock or safety actuator line held too low. In JTEKT's variable-ratio design a PNP transistor switches the lock coil, and the ECU holds the line low on purpose when it wants to lock, for instance after a motor or sensor fault or a broken cable. An unintended short to ground therefore looks like a permanent lock request: the solenoid cannot lift the arm, and the steering stays mechanically coupled. GM's active front steering patent locks the motor electrically first and falls back to the mechanical lock if that has not happened within about 42 ms. No maker publishes C0621. The car steers normally but without the variable feature, and a warning appears.

Likely causes

Lock solenoid wire shorted to ground in the column or gear harness
Shorted turns in the lock solenoid
Failed drive transistor in the steering module

Symptoms

  • Variable ratio or effort function off
  • Steering warning lamp or message

Repair estimate

DifficultyHardWorkshop job
Parts and labour€30–2,000
Time0.5–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

ves lock actuator

Related codes

C0620C0622C0623C061D

References: patents.google.com, patents.google.com, patents.google.com.