What Does C1223 Mean?
The ABS module is receiving a zero-speed signal from the left rear wheel speed sensor while the vehicle is moving. The sensor is failing to produce the expected AC voltage signal as the tone ring passes by. The ABS and traction control warning lights will be illuminated, and both systems will be deactivated.
Common Causes
35%
Failed or contaminated left rear wheel speed sensor
30%
Damaged wiring or corroded connector between sensor and ABS module
20%
Damaged or missing teeth on the left rear tone ring
10%
Excessive sensor-to-ring air gap from worn wheel bearing or improper installation
5%
ABS module internal failure on the left rear input channel
Diagnostic Steps
1
Monitor live data for all four wheel speed sensors while driving at 25+ mph — confirm the left rear reads 0 while the other three show correct and matching speeds.
2
Inspect the left rear wheel speed sensor and its connector for physical damage, corrosion, or moisture. Measure sensor resistance — expect 800-2000 ohms. Infinite resistance means an open sensor; near-zero means a short.
3
Raise the left rear wheel and spin it by hand while measuring AC voltage at the sensor connector — expect 100-700 mV AC. No output confirms sensor or tone ring failure.
4
Remove the sensor and inspect the tone ring for cracked, missing, or rust-filled teeth. On rear axle vehicles, check the differential-mounted reluctor ring for damage.
5
Perform a continuity check on the wiring from the left rear sensor connector to the ABS module harness connector, checking for opens, shorts to ground, and shorts to power.
Estimated Repair Cost
$80 - $350
Parts + labor, varies by vehicle and location
The ABS module is receiving a zero-speed signal from the left rear wheel speed sensor while the vehicle is moving. The sensor is failing to produce the expected AC voltage signal as the tone ring passes by. The ABS and traction control warning lights will be illuminated, and both systems will be dea...
The most common cause of C1223 (Left Rear Wheel Speed Sensor Input Signal is 0) is: Failed or contaminated left rear wheel speed sensor
Typical repair costs for C1223 range from $80 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
ABS and traction control are disabled for the left rear corner. Standard braking remains functional, but the vehicle will not have anti-lock braking capability during panic stops. Use extra caution on wet, icy, or gravel surfaces. The vehicle is safe to drive to a repair facility at moderate speeds.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C1223 to identify the root cause.
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Quick Info
Category
Chassis
System
ABS / Traction Control
Difficulty
Type
Manufacturer
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