Chassis, generic

C0518 Left Front Wheel Speed Sensor - Mechanical

Check engine lightUsually off
EmissionsNot relevant
Drive cycleRequired
Limp modePossible

C0518 points to a mechanical rather than electrical problem at the left front speed sensor: wrong part, wrong position, a damaged or soiled encoder, or play in the hub. No manufacturer documents this exact code publicly; GM's tables and Mitsubishi's index file such faults under range or correlation codes instead. The mechanics are well described elsewhere. GM bulletin PIT5950 for Silverado and Sierra 1500 warns that left and right front sensors look alike, that a swapped part keeps setting codes, and that the flat side of the tip must face the magnetic encoder ring on the wheel bearing. An Infiniti bulletin asks technicians to check the sensor head and the encoder for dirt, cracks, missing teeth, corrosion and looseness, since contamination alone can cause intermittent faults.

Likely causes

Magnetic encoder or tone ring dirty, cracked or missing teeth
Sensor for the other side fitted or tip turned away from the encoder
Worn or loose left front hub bearing changing the air gap

Symptoms

  • ABS and stability lamps on, often recurring after a repair
  • Uneven or missing left front speed reading at low speed

Repair estimate

DifficultyMediumDIY possible
Parts and labour€0–500
Time0.3–3 h

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

Parts involved

wss lftone ring lf

Related codes

C0519C051AC051BC0501C0505C0555

References: static.nhtsa.gov, static.nhtsa.gov, hella.com.