C0300ABS / Traction

Rear Speed Sensor Circuit

C0300 indicates a fault in the rear speed sensor circuit, used on some vehicles with a single rear or vehicle speed sensor. The ABS or control module is not getting a valid rear speed signal.

🚗 Yes, but ABS and related systems may be disabled, so fix it soon.

MEDIUM

severity

🎯 Top Causes, Ranked by Likelihood

#1Failed speed sensor$50-$250

40%

The rear or vehicle speed sensor has failed.

#2Wiring or connector damage$50-$300

30%

Damaged wiring or corroded connector at the sensor.

#3Damaged tone/reluctor ring$100-$400

20%

Damage to the ring or gear the sensor reads.

#4Excessive air gap or debris$0-$100

10%

Debris or a loose sensor corrupts the signal.

🩺 Common Symptoms

ABS warning light on
Speedometer may be erratic or dead
Traction control light on
Transmission shifting may be affected

💰 Repair Cost: DIY vs Shop

DIY Cost

$50-$300

Shop Cost

$150-$450

📋 Free OBD2 Code Cheat Sheet

The 50 most common codes with likely cause and DIY fix cost. Sent once, no spam.

🔧 How to Diagnose C0300

1Scan and confirm the rear speed sensor code

2Inspect the sensor, connector, and tone ring

3Check wiring continuity and the sensor air gap

4Compare live speed data to a scan tool reading

❓ Frequently Asked Questions

Can I drive with C0300?

Yes, but ABS, traction, and even the speedometer may be affected, so drive carefully and fix it soon.

How much to fix C0300?

A speed sensor is typically $150-$450 installed, or less if you DIY.

What causes C0300 most often?

A failed rear or vehicle speed sensor or damaged wiring at the sensor.

🔗 Related Codes

C0201C0045C0050C0035