2018-2025 Honda Odyssey Radar Sensor: Solving ACC & CMBS Warning Lights
This guide explains common failures, replacement costs, and the critical calibration needs for the front radar sensor in 2018-2025 Honda Odyssey minivans.
- A replacement radar sensor, whether new or used, REQUIRES professional calibration with special tools. This is not a DIY job.
- A cascade of warning lights (ACC, CMBS, etc.) usually points to a single fault, not multiple broken systems.
- Before any repair, clean the Honda emblem on the grille and check the vehicle's battery, as both can cause false warnings.
- A new OEM sensor is very expensive ($600+), making a verified used OEM part a good value, but the mandatory calibration cost ($250+) must be factored in.
Symptoms of Failure
A failing or obstructed radar sensor on a 2018-2025 Honda Odyssey will typically cause a cascade of warning lights on the dashboard. Because multiple safety systems rely on this single sensor, you will likely see several error messages appear at once.
- Dashboard Warning Lights: The most common symptom is the simultaneous appearance of warnings for "Adaptive Cruise Control (ACC) Problem," "Collision Mitigation Braking System (CMBS) Problem," and "Road Departure Mitigation System Problem."
- Disabled Cruise Control: When these errors are present, both Adaptive Cruise Control and standard cruise control will be disabled.
- "Radar Obstructed" Message: In some cases, especially in winter or bad weather, the driver information display may show a "Radar Obstructed" message. This is often temporary and can be caused by snow, ice, or heavy dirt blocking the sensor. 🎬 Watch: Quick tips for fixing a radar obstructed message
- Phantom Braking: While less common, a misaligned or failing sensor can cause false alerts or unnecessary, sudden braking from the CMBS system.
Pro Tip: Before assuming the sensor has failed, thoroughly clean the flat, smooth Honda emblem on the front grille with mild soap and water. Road grime, bugs, snow, or ice can block the radar signal and trigger error messages. Often, a simple cleaning and restarting the vehicle will resolve the issue.
Known Issues, Recalls, and Technical Service Bulletins (TSBs)
While there are no direct recalls for the front radar sensor itself on the 2018-2025 Odyssey, the Honda Sensing system it belongs to has been the subject of numerous owner complaints and some related service bulletins.
- TSB A21-068: For other Honda models like the Accord, Civic, and CR-V, this TSB addresses the DTC P2583-76 (Misalignment Millimeter Wave Radar) which can be triggered by snow or ice buildup. While not specific to the Odyssey, the principle is the same. 🎬 See how to fix code P2583-76 and TSB 21-068
- General ADAS Complaints: The 2018+ Odyssey generation has a high volume of NHTSA complaints related to its safety systems, including false alerts and phantom braking reports.
- Weak Battery Issues: Many Honda owners report that a weak or dying 12-volt battery can cause a variety of random electronic issues, including spurious ADAS warning lights. If you experience intermittent warnings, especially on startup, have your battery's health checked before replacing expensive sensors.
- MOST Bus Network Issues (TSB 20-049): While not directly for the radar, this TSB addresses issues with loose connectors in the vehicle's communication network that can cause various electronic problems, including popping speakers and display issues. This highlights the sensitivity of the vehicle's interconnected electronic systems.
Buying a Used Radar Sensor
Given the high cost of a new OEM radar sensor, a used unit can be a cost-effective option. However, this is a sensitive electronic part, and careful inspection is crucial.
Physical Inspection:
- Check the Lens: The front face of the sensor must be free of cracks, deep scratches, or any signs of delamination. Any physical damage can distort the radar waves.
- Inspect the Housing: Look for cracks or damage to the plastic casing and mounting points. A sensor from a vehicle with heavy front-end damage should be avoided, even if it looks intact.
- Examine the Connector: The electrical connector pins should be straight, clean, and free of corrosion. Bent or corroded pins can cause intermittent connection problems.
Compatibility:
Warning: You MUST match the part number exactly. There are different part numbers for different year ranges. Using the wrong part number will result in system incompatibility.
- 2018-2020 Models: Check for part number 36931-THR-A11 (Note: This is sometimes listed as a rear blind spot radar, but front radar part numbers can be similar. Verify with the seller).
- 2021-2025 Models: Check for part number 36803-THR-A01.
- Always verify the part number from your original sensor before purchasing a replacement.
Replacement & Calibration
Physically replacing the radar sensor is relatively straightforward, typically involving the removal of the front grille or bumper cover to access a few bolts and an electrical connector. However, the critical and most difficult part of the job is the post-installation calibration.
Warning: Replacement of the millimeter wave radar sensor requires a mandatory aiming (calibration) procedure. This is not an optional step. Failure to calibrate the sensor will result in the system not working and can create a serious safety risk if it provides inaccurate data to the collision mitigation system. This procedure requires specialized equipment like targets and a compatible high-level scan tool (like the Honda i-HDS) and cannot be performed by most DIY mechanics.
Cost Comparison
| Part/Service | Estimated Cost | Notes |
|---|---|---|
| New OEM Sensor | $600 - $1,100 | Price varies by part number and dealer. For example, part 36803-THR-A01 has an MSRP of over $870 and 36931-THR-A11 is over $1,000. |
| New Aftermarket Sensor | Not Generally Available | Due to the complexity and safety-critical nature, reliable aftermarket versions of this specific sensor are not common. |
| Used OEM Sensor | $150 - $400 | Price depends on condition and supplier. Offers significant savings but requires careful inspection. |
| Shop Labor (Installation) | $100 - $200 | Estimated 1-2 hours for physical replacement. |
| Shop Labor (Calibration) | $250 - $500 | This is a separate, specialized procedure that can be costly. A dealership or a well-equipped independent shop is required. |
Frequently Asked Questions (FAQ)
Why did all my dashboard warning lights (ACC, CMBS, LKAS) come on at once?
This usually indicates a single fault in the Honda Sensing system. All these features rely on the same forward-facing camera and radar sensor. The most common culprits are an obstructed sensor (dirt, snow), a failing sensor, a weak battery, or a problem with the camera.
🎬 Watch: How to reset a flashing CMBS warning lightCan I replace the radar sensor myself?
While you might be able to physically swap the part, you cannot complete the job at home. The sensor requires a mandatory calibration procedure using specialized dealer-level tools and targets to aim the radar correctly. Skipping this step will leave the system inoperative and potentially unsafe.
The dealer quoted me $2,500 for a repair. Is that right?
A high quote like this typically includes the cost of a new OEM sensor (around $700-$1,100), diagnostic time, labor for installation, and the separate, expensive calibration procedure. While high, it can be accurate for a full dealer repair. Sourcing a used OEM part can significantly lower the total cost, but the professional calibration is still required.
Do I have to fix the radar sensor?
You can continue to drive the vehicle without a functioning radar sensor, but all associated safety features like Adaptive Cruise Control and Collision Mitigation Braking will be disabled. This means the vehicle will not automatically brake to prevent a collision. Standard cruise control will also be unavailable.
Helpful Videos
Technical Specifications
OEM Part Numbers: 36803-THR-A01 36931-THR-A11
The front radar sensor is a millimeter wave radar unit located behind the front grille emblem. It is a key input for the Honda Sensing suite of Advanced Driver Assistance Systems (ADAS).
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Honda Odyssey: