What Does C0237 Mean?
This code indicates the ABS control module has detected an inconsistent or erratic signal from one or both rear wheel speed sensors. The wheel speed signal is fluctuating unexpectedly, reading too high, too low, or intermittently cutting out during vehicle operation. This affects the anti-lock braking system, traction control, and stability control functions, as these systems rely on accurate wheel speed data to function properly.
Safety Warning
Vehicle should not be driven except to a repair facility, as ABS, traction control, and stability control systems are likely disabled. Emergency braking performance is significantly compromised, especially on wet or slippery surfaces, greatly increasing accident risk.
Common Causes
35%
Damaged or contaminated rear wheel speed sensor or tone ring with debris, metal shavings, or corrosion causing irregular signal generation
30%
Damaged, chafed, or corroded wiring or connector at the rear wheel speed sensor causing intermittent connection or short circuits
20%
Excessive wheel bearing play or worn wheel bearing allowing sensor air gap to vary and create erratic readings
10%
Incorrect wheel speed sensor air gap due to improper installation or sensor mounting bracket damage
5%
Failed wheel speed sensor with internal winding breakdown or magnetic pickup degradation
Diagnostic Steps
1
Step 1: Using live data on the scan tool, monitor all four wheel speed sensor readings while driving at 5-15 mph in a safe area. Compare rear wheel speeds to front wheels and to each other, noting any dropouts, spikes, or values that don't match vehicle speed
2
Step 2: Perform visual inspection of both rear wheel speed sensors, wiring harnesses, and connectors for physical damage, corrosion, chafing, or water intrusion. Inspect tone rings for missing teeth, cracks, debris buildup, or metal contamination
3
Step 3: With wheels off the ground, use a digital multimeter to measure AC voltage output from each rear wheel speed sensor while rotating the wheel by hand at approximately 1 revolution per second (should produce 200-1000mV AC varying with speed). Check resistance across sensor terminals (typically 800-1400 ohms for passive sensors)
4
Step 4: Check rear wheel bearing play by grasping tire at 12 and 6 o'clock positions and rocking wheel to detect excessive movement. Measure sensor air gap with feeler gauge (typically 0.020-0.050 inches) or verify proper seating if sensor is magnetic
5
Step 5: Inspect wiring continuity from sensor connector to ABS module connector using wiring diagram, checking for opens, shorts to ground, or shorts to power. Wiggle harness while monitoring resistance to identify intermittent faults
6
Step 6: Clear codes, test drive vehicle while monitoring live data, and verify the erratic signal is eliminated. Confirm ABS, traction control, and stability control lights remain off after repair
Estimated Repair Cost
$120 - $650
Parts + labor, varies by vehicle and location
This code indicates the ABS control module has detected an inconsistent or erratic signal from one or both rear wheel speed sensors. The wheel speed signal is fluctuating unexpectedly, reading too high, too low, or intermittently cutting out during vehicle operation. This affects the anti-lock braki...
The most common cause of C0237 (Rear Wheel Speed Signal Erratic) is: Damaged or contaminated rear wheel speed sensor or tone ring with debris, metal shavings, or corrosion causing irregular signal generation
Typical repair costs for C0237 range from $120 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle should not be driven except to a repair facility, as ABS, traction control, and stability control systems are likely disabled. Emergency braking performance is significantly compromised, especially on wet or slippery surfaces, greatly increasing accident risk.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to C0237 to identify the root cause.
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Quick Info
Category
Chassis
System
Anti-lock Braking System (ABS) / Traction Control / Stability Control
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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