What Does C1191 Mean?
The left front wheel speed sensor input circuit is shorted to ground. The ABS module detects a constant low (ground-level) signal on the LF sensor input instead of the expected alternating speed signal. The module cannot determine the left front wheel's rotational speed, so ABS, traction control, and stability control are disabled.
Safety Warning
ABS and stability control are disabled. The left front wheel handles a significant portion of braking force, making this a serious safety concern. Avoid aggressive braking and slippery conditions until repaired. Drive to a repair facility promptly.
Common Causes
35%
Sensor wiring chafed against the steering knuckle, strut, or suspension components and grounding out
25%
LF wheel speed sensor internally shorted to ground through a cracked housing contacting the knuckle
20%
Water intrusion in the sensor or intermediate connector causing a ground path
15%
Damaged wire insulation in the wheel well area from road debris or salt corrosion
5%
ABS module input driver grounded internally
Diagnostic Steps
1
Disconnect the LF wheel speed sensor at the knuckle. Clear codes. If the code changes to an open/general failure code, the sensor is shorted to ground internally — replace it.
2
With the sensor disconnected, measure resistance from each harness-side connector pin to chassis ground. Both should read OL. A low reading (near 0 ohms) on either pin means the wire is grounded in the harness.
3
Visually inspect the sensor wire routing from the knuckle up through the wheel well and into the engine bay. Look for bare copper where the wire contacts metal suspension parts, body panels, or bolts.
4
Check for a previous repair with electrical tape that may have failed, exposing the wire. Also check for rodent damage to the wire insulation.
5
Turn the steering wheel fully left and right while monitoring resistance. The LF sensor wiring flexes with steering input, and a short that only appears at certain steering angles indicates the exact location of the chafe.
Estimated Repair Cost
$50 - $350
Parts + labor, varies by vehicle and location
The left front wheel speed sensor input circuit is shorted to ground. The ABS module detects a constant low (ground-level) signal on the LF sensor input instead of the expected alternating speed signal. The module cannot determine the left front wheel's rotational speed, so ABS, traction control, an...
The most common cause of C1191 (Speed Wheel Sensor LF Input Short Circuit To Ground) is: Sensor wiring chafed against the steering knuckle, strut, or suspension components and grounding out
Typical repair costs for C1191 range from $50 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
ABS and stability control are disabled. The left front wheel handles a significant portion of braking force, making this a serious safety concern. Avoid aggressive braking and slippery conditions until repaired. Drive to a repair facility promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C1191 to identify the root cause.
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Quick Info
Category
Chassis
System
ABS / Traction Control
Difficulty
Type
Manufacturer
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