C0045 medium Severity

C0045: Left Rear Wheel Speed Sensor Circuit Malfunction

ABS/ESC traction control and stability control may be reduced or disabled, increased stopping distances and safety risk.

Overview

DTC C0045 indicates a malfunction in the left rear wheel speed sensor circuit affecting ABS and electronic stability control systems, typically due to sensor fault, wiring issues, or module communication errors.

Common Symptoms

  • ABS warning light illuminated
  • Traction control/stability control lights on
  • Loss of ABS or ESC assistance
  • Possible uneven braking behavior

Most Common Causes

Faulty left rear wheel speed sensor high

Sensor fails to send proper signal causing ABS controller to flag circuit error.

Damaged or corroded wiring harness or connector high

Open, shorted, or poor electrical connections in harness common in circuit faults.

ABS or ESC control module communication failure medium

Module not reading sensor data correctly; less common but documented.

Reluctor ring damage or wheel hub issues medium

Mechanical issues can cause abnormal sensor readings and trigger code.

Diagnostic Steps

  1. Connect OBD-II scanner and confirm C0045 active; note any related codes.
    Expected: C0045 present, possibly alongside other wheel speed or ABS related codes.
    Interpretation: Validates direction of left rear wheel speed circuit investigation.
  2. Visually inspect left rear wheel speed sensor and wiring harness.
    Expected: Check for physical damage, corrosion, frayed wires, loose connectors.
    Interpretation: Identify obvious electrical/connector problems.
  3. Test sensor output with multimeter (resistance/voltage) while spinning wheel.
    Expected: AC voltage signal that varies with wheel speed; resistance within spec.
    Interpretation: No or abnormal signal suggests faulty sensor or wiring.
  4. Check ABS/ESC control module communication using scan tool live data.
    Expected: Consistent valid wheel speed readings for all wheels.
    Interpretation: Irregular data points to controller communication issue.

Repair Solutions

Replace left rear wheel speed sensor medium
Estimated Cost: $75 - $300

Cost varies by vehicle make/model and labor rates.

Repair or replace damaged wiring/connectors medium
Estimated Cost: $50 - $200

Includes harness repair and corrosion cleaning.

Service or replace ABS/ESC control module hard
Estimated Cost: $800 - $1400

High cost and complexity; recommended after sensor and wiring ruled out.

Common Misdiagnoses

Avoid these common diagnostic mistakes:

  • Interpreting C0045 as a generic brake pressure sensor code without vehicle-specific context

Frequently Asked Questions

What is the definition of the C0045 engine code?

When your OBD-II scanner reads C0045, it means: Left Rear Wheel Speed Sensor Circuit Malfunction. This code is related to the vehicle's Sensors.

Is it safe to drive with a C0045 code?

The C0045 code is considered medium severity. ABS/ESC traction control and stability control may be reduced or disabled, increased stopping distances and safety risk.

Symptoms associated with DTC C0045

Common symptoms include: ABS warning light illuminated, Traction control/stability control lights on, Loss of ABS or ESC assistance. You might also notice the Check Engine Light is on.

What causes the C0045 code?

The most common causes are: Faulty left rear wheel speed sensor, Damaged or corroded wiring harness or connector, ABS or ESC control module communication failure.

How much does it cost to fix C0045?

Expect to pay around $200 if the issue is a Repair or replace damaged wiring/connectors, but up to $1400 if the Service or replace ABS/ESC control module needs replacement.

Does code C0045 apply to Mercedes vehicles?

The C0045 code is a generic powertrain code, meaning it applies to almost all makes and models, such as Honda, Toyota, VW, Ford, and Chevy.

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