2021 Honda Civic ACC Warning Message TSB

Owners of 2021 Honda Civic and Insight vehicles may encounter an "Adaptive Cruise Control System Problem" message appearing in their multi-information display. This issue, which can trigger the ACC warning lamp, is particularly common in low or near-freezing ambient temperatures. Honda Service News Article A21080A, also identified as Service Bulletin (S/B) 21-068, provides guidance on this condition.

This article revises a previous version posted in August 2021, indicating ongoing attention to this specific issue. The Honda Civic ACC warning is often a result of environmental factors affecting the vehicle's radar-based safety systems.

Symptoms of the Adaptive Cruise Control System Problem

When the Adaptive Cruise Control (ACC) system encounters a problem, drivers will typically see the message "Adaptive Cruise Control System Problem. See Your Dealer." displayed on the multi-information display. The "ACC" indicator may also illuminate. This message is most likely to appear when the vehicle is driven in freezing conditions, suggesting a link to environmental factors.

Associated Fault Codes

The primary diagnostic trouble code (DTC) associated with this issue is DTC 2583-76. This code indicates a problem with the ACC warning lamp and is often triggered in low or near-freezing ambient temperatures.

Diagnosis and Trigger Conditions

The primary cause for the "Adaptive Cruise Control System Problem" and the Honda Civic ACC warning in cold weather is snow or ice buildup on the radar sensor. This sensor is crucial for the ACC system's operation and is located behind the front grille. When debris, such as dirt, snow, or ice, obstructs the sensor, the system cannot function correctly and displays the warning message.

Occasionally, the message may appear temporarily even without visible obstruction, possibly due to surrounding environmental factors like driving through a tunnel. In such cases, the system may require time to recalibrate.

Owner Action and Repair Procedure

If you experience the "Adaptive Cruise Control System Problem" message in your 2021 Honda Civic or Insight, Honda Service Bulletin 21-068 outlines a simple procedure:

1. Stop Safely: Pull over to a safe location as soon as possible.
2. Clean the Radar Area: Locate the radar sensor in the front grille. Gently wipe off any debris, such as dirt, snow, or ice, using a soft cloth. The bulletin includes diagrams showing the radar location for various models, including the Civic, Accord, CR-V, and Insight, typically a rectangular sensor behind the lower grille.
3. System Reset: The warning message will not disappear immediately after cleaning. The system needs to detect that the obstruction has been removed. This usually happens as you continue driving.
4. Recalibration: If no debris is present and the message persists, it may be a temporary environmental issue. Drive the vehicle, and the system should recalibrate. This process typically takes about 20 minutes but can extend up to 120 minutes, depending on the driving environment.

Important Warnings for Owners

When cleaning the radar sensor area to address the Honda Civic ACC warning, it is crucial to follow these guidelines:

• Do not apply too much force: Excessive pressure can damage the delicate radar sensor.
• Do not use harsh chemicals: Avoid using polishing powders, benzine, or thinners, as these can harm the sensor's surface or internal components.

Following these precautions will help prevent further damage to your vehicle's Adaptive Cruise Control system.

Superseded Information

This Honda Service News Article A21080A (S/B 21-068) is a revised version of a previous article on the same topic, initially posted in August 2021. This indicates Honda's continued effort to provide updated information and solutions for this specific issue.

NHTSA ID: 10244299