C1230
Speed Wheel Sensor Rear Center Input Circuit Failure
Chassis Chassis/Safety ABS/Wheel Speed Sensor 🔴 Serious — Stop or limit driving
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What This Actually Means
In plain language — no jargon

Your vehicle's rear center wheel speed sensor isn't sending a proper signal to the computer, like a speedometer that suddenly stops working. This affects anti-lock braking and traction control systems that rely on knowing wheel rotation speed.

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Symptoms You May Notice
3 known symptoms for this code
ABS warning light illuminated on dashboard
Traction control disabled or malfunctioning
Vehicle may enter limp mode with reduced stability control
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors the alternating voltage signal from the rear center wheel speed sensor as the wheel rotates. It expects a continuous AC signal with consistent frequency and amplitude that correlates to wheel speed. A break in the signal, short circuit, or open circuit triggers this fault.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Sensor Signal Frequency 10-10,000 Hz (varies with speed) No signal or erratic frequency below threshold
Signal Voltage 0.2 to 5+ volts AC Stuck voltage, open circuit, or short to ground
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Wheel speed sensor connector
Inspect and reseat the connector at the rear center wheel for corrosion or loose pins.
2
Wiring harness
Check for damaged, pinched, or corroded wiring between sensor and ABS module under vehicle.
3
Wheel speed sensor
Replace the rear center speed sensor if connector and wiring are intact and undamaged.