C1091 – OBD-II DTC

OBD-II DTC C1091 – Speed Wheel Sensor All Coherency Failure

DTC C1091 meaning

DTC C1091 refers to a diagnostic trouble code indicating a “Speed Wheel Sensor All Coherency Failure.” This code is generated when the vehicle’s onboard diagnostic system detects a discrepancy in the signals received from the wheel speed sensors. These sensors are crucial for various systems, including anti-lock braking systems (ABS) and traction control, as they monitor the rotational speed of each wheel.

DTC C1091 symptoms

Common symptoms associated with DTC C1091 may include:

• Illumination of the ABS warning light on the dashboard
• Loss of traction control functionality
• Inconsistent or erratic braking performance
• Potential activation of the stability control system
• Unusual noises during braking

DTC C1091 causes

Several factors can lead to the triggering of DTC C1091, including:

• Faulty wheel speed sensors
• Wiring issues, such as damaged or corroded connectors
• Faulty ABS control module
• Improperly installed or misaligned sensors
• Mechanical issues with the wheel assembly

DTC C1091 seriousness

DTC C1091 is considered a serious issue as it affects the vehicle’s braking and stability control systems. If left unaddressed, it can lead to compromised vehicle safety, especially in slippery or emergency conditions. It is advisable to diagnose and repair the issue promptly to ensure safe vehicle operation.

How to diagnose DTC C1091

To diagnose DTC C1091, follow these steps:

1. Use an OBD-II scanner to confirm the presence of the C1091 code.
2. Inspect the wheel speed sensors for physical damage or disconnection.
3. Check the wiring and connectors for corrosion or wear.
4. Test the resistance and output voltage of the wheel speed sensors.
5. Examine the ABS control module for faults or error codes.
6. Perform a road test to observe the behavior of the ABS and traction control systems.

How to fix DTC C1091 step-by-step instructions

To fix DTC C1091, follow these steps:

1. Identify and replace any faulty wheel speed sensors.
2. Repair or replace damaged wiring and connectors.
3. Ensure proper installation and alignment of the wheel speed sensors.
4. Test the ABS control module and replace it if necessary.
5. Clear the DTC using an OBD-II scanner.
6. Perform a road test to verify that the issue has been resolved.

How to erase DTC C1091

To erase DTC C1091, follow these steps:

1. Connect an OBD-II scanner to the vehicle’s diagnostic port.
2. Turn on the ignition without starting the engine.
3. Access the diagnostic menu on the scanner.
4. Select the option to clear or erase trouble codes.
5. Confirm the action and wait for the scanner to complete the process.
6. Disconnect the scanner and start the vehicle to ensure the code does not reappear.

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