C1145 – Speed Wheel Sensor RF Input Circuit Failure

Reinier

By Reinier (Contact Me)
Last Updated 2020-08-13
Automobile Repair Shop Owner

Trouble CodeFault LocationProbable Cause
C1145 Speed Wheel Sensor RF Input Circuit Failure

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What Does Code C1145 Mean?

OBD II fault code C1145 is a manufacturer-specific trouble code that is defined by carmaker Ford as “Speed Wheel Sensor RF Input Circuit Failure” and is set when the PCM (Powertrain Control Module) detects a failure, defect or malfunction in the input circuit of wheel speed sensor on the right front wheel.

All modern vehicles use dedicated sensors located at each wheel to monitor wheel speed. The purpose of measuring wheel speed is to supply the ABS and other control modules with information on the rotational speed of each wheel. The principal user of this information is the ABS control module, which has the function of modulating brake pressure to wheels that rotate at slower rates than others do during braking to maximize braking performance by preventing wheels from locking up during aggressive braking.

As a practical matter, a wheel speed sensor generates magnetic signals when the teeth on a rotating reluctor ring pass in front of the sensing element, which signals are converted into voltages by the ABS control module. Thus, by “counting” the number of signals at each wheel, the ABS, or other control modules can compare the frequency of the signals at each wheel as a means of calculating the rotational speed of each wheel relative to all the other wheels.

While this data is primarily used by the ABS system to modulate brake pressure at individual wheels during aggressive braking events, the same data is also used by other control modules. For instance, the traction control system applies modulated brake pressure to a spinning wheel to transfer torque to the non-spinning wheel, while the stability control system can supply modulated braking forces to individual wheels to force the vehicle into following a line dictated by the steering angle sensor.

Similarly, hill descent control system use this data to apply braking forces to all the wheels to control the vehicle’s speed when negotiating steep descents, while accident mitigation systems use this data to apply more braking force (sometimes autonomously) to the wheels than a driver could, while preventing wheels from locking up at the same time.

From the above, it should be obvious that wheel speed sensors are safety-critical components in any modern vehicle’s brake system. Therefore, if the PCM or any other control module detects a fault, failure, or defect in the right front wheel speed sensors’ circuit(s) that interrupts the communication between the right front wheel speed sensor and implicated control modules, one or more control modules will set code C1145 and illuminate all relevant waning lights as result.

Where is the C1145 sensor located?

This image shows the location (arrowed in red) if the wheel speed sensor on the front wheel of a Ford Ranger 4 × 4 truck. The component arrowed in green is the actual sensor that has been removed from its mounting hole for clarity. Note though that in all cases, both in passenger vehicles and trucks, the wheel speed sensor will be located in the wheel hub or steering knuckle, and close to the wheel bearing that often contains the reluctor ring, or to the drive shaft that is fitted with a reluctor ring.

What are the common causes of code C1145?

Typical causes of code C1145 are much the same across all Ford applications, and could include one or more of the following-

  • Damaged, burnt, shorted, disconnected, or corroded wiring and or connector (Most common)
  • Blown fuse or fusible link
  • Excessive accumulation of dirt, mud, or other debris between the sensor and the reluctor ring
  • Incorrect air gap between the sensing element in the sensor and the reluctor ring
  • Defective or faulty wheel speed sensor
  • Incorrectly installed front wheel bearing
  • Use of an unsuitable, incorrect, or substandard aftermarket wheel speed sensor
  • Excessively worn front wheel bearing
  • Failed or failing ABS control module (Unlikely, but not impossible)

What are the symptoms of code C1145?

Most symptoms of code C1145 on Ford applications are largely similar, and could include one or more of the following-

  • Stored trouble code and illuminated ABS warning light
  • In most cases, additional codes relating to stability control, and traction control, and other driver-assist/safety systems may also be present, and traction control and/or stability control warning lights may also be illuminated
  • ABS brake function will be disabled, although normal braking will be available
  • Cruise control, stability control, traction control, and other driver-assist systems that use the ABS system to work will be disabled or will not be available

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