ABS Code C1156: Left Front Wheel Speed Sensor Open Circuit
The C1156 code indicates that the ABS control module has detected an open circuit in the left front wheel speed sensor circuit. This means there is no electrical continuity between the ABS module and the sensor, preventing the module from reading wheel speed. As a result, the ABS, traction control, and stability control systems are disabled to prevent incorrect operation.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty left front wheel speed sensor (internal coil open)
- Damaged, cut, or corroded wiring between the sensor and the main harness connector
- Loose, disconnected, or corroded terminals at the sensor or ABS module connector
- Internal failure of the ABS hydraulic control unit (HCU) or ABS module (less common)
- Damaged or incorrect wheel bearing (tone ring carrier)
3. Symptoms You Will Notice
- ABS warning light illuminated on the dashboard
- Traction control and stability control warning lights on
- ABS, traction control, and stability control systems inoperative
4. Step-by-Step Diagnosis
Scan the ABS module for codes and verify C1156 is present.
Visually inspect the left front wheel speed sensor wiring and connector for damage, corrosion, or loose connection.
Measure the resistance of the wheel speed sensor at the connector; compare to manufacturer specifications (typically 1-2 kΩ). An open circuit indicates a faulty sensor.
Check for AC voltage output from the sensor while spinning the wheel; no voltage suggests a sensor or wiring issue.
Inspect the tone ring on the wheel bearing for damage or missing teeth.
If sensor and wiring are good, test continuity from the sensor connector to the ABS module; repair open circuits as needed.
If all else is normal, suspect a faulty ABS module and perform further module diagnostics.
5. Frequently Asked Questions
Is it safe to drive?▼
You can still drive the vehicle, but without ABS, traction control, or stability control. Braking performance is reduced in slippery conditions, and the vehicle may be unstable during hard braking or on low-traction surfaces. It is recommended to have the issue repaired promptly.
How much does it cost to fix?▼
Repair costs typically range from $100 to $400, depending on the cause. A new wheel speed sensor costs $30–$100, plus labor (0.5–1 hour). Wiring repairs are usually $100–$200. ABS module replacement can exceed $1,000.