C1700 — Left Rear Sensor Circuit Failure #

Note: The description for code C1700 may vary depending on the vehicle manufacturer (OEM). Always consult your vehicle’s service manual for the most accurate definition.

• Left Rear Sensor Circuit Failure (Ford, Nissan, Subaru, Toyota)
• Left Rear Wheel Speed Sensor Circuit Malfunction (Mazda)
• Rear Left ABS Wheel Sensor Circuit Failure (Hyundai, Kia)

Summary of Code C1700 #

C1700 is a diagnostic trouble code (DTC) that indicates the vehicle’s onboard computer has detected an electrical fault in the circuit of the left rear sensor. Typically, this refers to the wheel speed sensor used by anti-lock braking systems (ABS) or traction control systems. When the circuit is disrupted—due to wiring issues, sensor failure, or connector problems—the module cannot reliably read the left rear wheel’s speed or position. As a result, safety functions like ABS or traction control may be limited or disabled. Prompt attention to this code ensures optimal braking performance and vehicle safety.

Common Symptoms for Code C1700 #

When C1700 is triggered, the vehicle usually presents clear warning signs. Drivers may notice dashboard lights or changes in braking behavior. While the car may still operate normally in basic conditions, the failure of advanced safety systems should not be ignored.

• ABS warning light illuminated
• Traction control or stability control light on
• Possible “brake” warning light
• Loss of anti-lock braking function
• Pulsing or unusual feedback in brake pedal during hard stops
• Possible speedometer irregularities or errors

Likely Causes for Code C1700 (By Frequency) #

The most common sources of C1700 involve electrical disruptions or sensor malfunctions. Understanding these causes helps in targeting diagnostics and repairs efficiently.

1. Damaged or corroded wiring to the left rear wheel sensor
2. Faulty left rear wheel speed sensor itself
3. Loose, disconnected, or corroded sensor connector
4. Faulty sensor reluctor ring (the toothed ring or magnet used for wheel speed detection)
5. Module failure (rare): ABS or traction control module internal fault

Step-by-Step Diagnosis for Code C1700 #

Diagnosing C1700 requires a systematic approach to avoid misdiagnosis and unnecessary part replacements. Follow these steps to accurately pinpoint the fault:

1. Visually inspect the left rear wheel speed sensor and its wiring harness for physical damage, abrasion, or corrosion.
2. Check the sensor connector for secure attachment, corrosion, bent pins, or moisture intrusion.
3. Use a multimeter to measure sensor resistance and verify against OEM specifications. Open circuits or infinite resistance typically indicate sensor failure.
4. Inspect the sensor’s reluctor ring for missing teeth, cracks, or debris obstructing the signal.
5. If all hardware checks out, use a scan tool to monitor live data from wheel speed sensors while spinning the wheel by hand—compare readings from all wheels.
6. Check for additional related codes that could indicate a broader wiring or module issue.

Possible Repairs for Code C1700 #

Repair actions should directly address the cause identified during diagnosis. Always clear the code and test-drive the vehicle to confirm the repair before returning it to service.

• Repair or replace damaged wiring or connectors to the left rear wheel speed sensor
• Replace the left rear wheel speed sensor if it is out of spec or nonfunctional
• Clean or replace the reluctor ring if damaged or contaminated
• Clean and secure all connectors to prevent future corrosion
• If necessary, replace the ABS/traction control module (rare)

Is It Safe to Drive with Code C1700? #

Driving with code C1700 is generally not recommended for extended periods. While the basic braking system remains operational, the failure of the ABS and traction control systems significantly reduces vehicle safety in emergency maneuvers, slippery conditions, or sudden stops. If the only symptom is a warning light and normal braking is present, short-term local driving may be possible to reach a repair facility. However, do not delay repairs, especially if you notice abnormal brake behavior or plan to drive in challenging road conditions.

Vehicles Most Commonly Affected by Code C1700 #

While C1700 is a generic code, it is more frequently reported on certain makes and models, often due to sensor placement or harness routing vulnerabilities. The following vehicles are known to show this code more often, but it can occur on any modern car with ABS:

• Ford Focus, Escape, Explorer
• Nissan Altima, Sentra, Rogue
• Toyota Corolla, Camry, RAV4
• Subaru Outback, Forester
• Kia Sorento, Hyundai Santa Fe
• Mazda 3, Mazda CX-5

Common Mistakes & Best Practices for Code C1700 #

Technicians and DIYers alike sometimes overlook the basics or misinterpret symptoms. Avoid these pitfalls and follow these best practices for a smooth repair process:

• Do not replace the wheel speed sensor before checking wiring and connectors—these are often the real culprits.
• Always inspect the reluctor ring for physical damage or debris before condemning the sensor.
• When using a scan tool, compare data from all wheel speed sensors—intermittent or zero readings are strong diagnostic clues.
• Clear the code after repairs and perform a road test to ensure no recurrences.
• Consult OEM repair procedures for specific testing values and diagrams.

Express FAQ for Code C1700 #

Q: Can a faulty left rear sensor cause other ABS codes?
A: Yes, a bad sensor or circuit can sometimes trigger additional ABS or traction control codes related to system function or communication errors.

Q: Is it expensive to fix code C1700?
A: Repairs range from simple wiring fixes (low cost) to sensor replacement (moderate cost). Module replacement is rare and more expensive, but most cases are resolved with basic parts and labor.