Toyota ADAS Fault Codes: Radar, BSM and Camera Warnings Explained

A Diagnostic Trouble Code (DTC) describes a condition detected by an electronic control system. It may identify an aiming concern, an incomplete adjustment or a missing message from another module. It does not always identify the failed part.

Toyota code formats and component names vary between models, production years and system generations. Keep the complete code, any suffix, its description and the name of the module that recorded it. A scan screenshot is more useful than a shortened code remembered from the dashboard or an online search.

Use the table as an owner’s reference. Confirm its meaning against the exact vehicle’s Toyota repair information before selecting tests, a replacement part or calibration. Labels such as master, slave, A and B should not be converted into a universal left-hand or right-hand position.

These descriptions apply to Toyota systems that use the listed codes. Similar wording across two vehicles does not establish identical causes, component positions or repair procedures.

A lost-communication code means the reporting module did not receive an expected message. Possible causes include disconnected or damaged wiring, a connector problem, missing power or ground, a network fault or a malfunctioning module. The scan needs to establish which unit recorded the code and which communication path is affected.

U023387 concerns a side obstacle detection module B on applicable systems, commonly within the BSM system. It does not directly establish an incorrect horizontal angle. A replacement radar may subsequently need registration, configuration or aiming, but those requirements follow the confirmed repair.

U111087 concerns clearance sonar or intuitive parking assist communication. These parking systems commonly use ultrasonic sensors; this code is not a direct instruction to calibrate the front radar or rear BSM sensors. The relevant parking control unit and its network connections need examination.

U023587 concerns communication with the front distance-range radar used by the cruise-control system. On applicable Toyota arrangements, the front recognition camera can report a missing radar message. Investigate the specified circuit and reporting module rather than assuming either sensor must be replaced.

The accompanying workshop photographs illustrate diagnostic work and warning displays. They are not evidence that every code in this reference table was recorded on those vehicles.

C1AC1 and C1AC2 refer to horizontal-axis misalignment of the master and slave BSM sensors on certain Toyota systems. Newer systems can use C1AC100 for rear side radar module B and C1AC200 for module A. The exact assignment and procedure must come from the applicable repair manual.

Inspection can involve the sensor, mounting bracket, rear bumper area and evidence of collision work. A displaced bracket or unsuitable installation may require correction before adjustment. Toyota also publishes model-specific technical bulletins, so the technician should check whether one applies instead of treating the code description as the complete diagnosis.

Sri Kuching’s published Vellfire record explicitly identifies C1AC1. That vehicle needed a faulty BSM module replacement, system calibration and horizontal beam-axis adjustment, followed by verification. It is an example of the completed repair for one vehicle, not a rule that every C1AC1 requires a new module.

C1A11 is associated with an incorrect front radar axial reference on certain systems; C1A14 can indicate that beam-axis adjustment has not been completed. C1A1100 is an optical-axis misalignment code used on some newer systems. Their detection conditions and repair paths are vehicle-specific.

An alignment-related label does not prove that a bracket has physically moved. Toyota has issued a software countermeasure for C1A11 on specified vehicles. That campaign cannot be assumed to apply to an Alphard or another model, but it demonstrates why the relevant technical information must be checked alongside installation and vehicle condition.

Where aiming is required, the technician checks the necessary vehicle preparation and follows the specified radar procedure. A successful fault-code deletion does not establish that adjustment has completed or that the underlying cause has been addressed.

C1AA800 concerns the optical axis of the forward recognition camera on applicable Toyota models. This camera is generally near the top of the windscreen and supplies visual information used by functions such as lane monitoring and collision assistance, depending on equipment.

The inspection may include the windscreen, camera bracket, installation and relevant vehicle conditions before the required aiming procedure. Camera targets, preparation and diagnostic functions can differ from radar equipment. A windscreen-camera fault should not be confused with reversing-camera or 360-degree parking-camera calibration.

Provide the make, model, year, full diagnostic report and exact warning wording. Include the timing of the concern and any recent bumper, windscreen, sensor or electrical work. Several warnings can stem from one communication problem, while another vehicle may have separate front and rear faults.

Sri Kuching in Taman Mastiara, Kuala Lumpur can use those details to discuss an inspection. The diagnostic findings determine whether the next step is installation correction, electrical work, programming, component replacement or a supported calibration procedure.