Chassis, generic

C0079 Variable Effort Steering

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

Covers the variable-effort (speed-sensitive) power steering function, where steering assist is high at low speed for easy parking and reduced at high speed for stability. The ABS/ESC or steering module uses vehicle speed to command the assist level through a solenoid-controlled hydraulic valve or an electric power-steering actuator. This code is set when the variable-effort actuator circuit is faulty, the commanded assist cannot be achieved, or the speed input it relies on is missing. A fault typically defaults steering to a fixed assist level and sets a warning; braking and ABS are unaffected. Because the function depends on a valid speed signal it can appear with wheel-speed or speed-signal codes. The entry follows the SAE J2012 generic definition and speed-sensitive power-steering design.

Likely causes

Variable-effort valve or actuator fault
Missing or wrong vehicle speed input
Harness or connector fault

Symptoms

  • Steering effort fixed or abnormal
  • Steering warning lamp or message
  • Heavy steering at low speed

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–1,200
Time0.6–3.5 h

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

Parts involved

ves system

Related codes

C0070C0051C0052

References: bosch-mobility.com, en.wikipedia.org.