# U1A4B on the 2016 Mazda MX\-5

The bulletins listed name this code in NHTSA's summary, or are about the same components. A bulletin or a recall listed here may apply to the model year. None of it is a diagnosis.

This code is specific to a manufacturer and is not described here.

## Bulletins for this model year that name U1A4B

- [11028099](https://open.wenmarpro.com/bulletins/11028099), 2026-02-03: If the right\-side Blind Spot Monitoring \(BSM\) control module is replaced for any reason, it is also necessary to replace the left\-side BSM control module in order to complete the radar aiming procedure. If the right\-side BSM control module is replaced alone, "Automatic Configuration" and "BSM Radar Aiming" cannot be completed due to a programming error in the module. In most cases, if the left\-side BSM control module is replaced alone, "Automatic Configuration" and "BSM Radar Aiming" can be completed without any problem \(See CAUTION below for more details\). Other possible symptoms that may be found if the right\-side BSM module is replaced alone: BSM aiming fails “BSM OFF" indicator ON Center Display warning message BSM failsafe \(No operation\) DTC U3000:54 stored in memory DTC U1A4B:54 stored in memory \(CX\-3, MX\-5 only\) NOTE: Since a new BSM control module does not retain the vehicle specification information, it is necessary to acquire and store the vehicle specification information transmitted via CAN communication from the combination meter through automatic configuration after replacement.
- [10225783](https://open.wenmarpro.com/bulletins/10225783), 2022-11-04: If the right\-side Blind Spot Monitoring \(BSM\) control module is replaced for any reason, it is also necessary to replace the left\-side BSM control module in order to complete the radar aiming procedure. If the right\-side BSM control module is replaced alone, "Automatic Configuration" and "BSM Radar Aiming" cannot be completed due to a programming error in the module. Other possible symptoms that may be found if the right\-side BSM module is replaced alone: \* BSM aiming fails \* "BSM OFF" indicator ON \* Center Display warning message \* BSM failsafe \(No operation\) \* DTC U3000:54 stored in memory \* DTC U1A4B:54 stored in memory \(CX\-3, MX\-5 only\)
- [10213449](https://open.wenmarpro.com/bulletins/10213449), 2022-06-06: BSM off indicator on with DTC U1A4B:97 or U3000:97
- [10155439](https://open.wenmarpro.com/bulletins/10155439), 2019-03-29: If the right\-side Blind Spot Monitoring \(BSM\) control module is replaced for any reason, it is also necessary to replace the left\-side BSM control module in order to complete the radar aiming procedure. If the right\-side BSM control module is replaced alone, "Automatic Configuration" and "BSM Radar Aiming" cannot be completed due to a programming error in the module. Other possible symptoms that may be found if the right\-side BSM module is replaced alone: BSM aiming fails, “BSM OFF" indicator ON, Center Display warning message, BSM failsafe \(No operation\), DTC U3000:54 stored in memory, DTC U1A4B:54 stored in memory \(CX\-3, MX\-5 only\).
- [10120383](https://open.wenmarpro.com/bulletins/10120383), 2017-10-21: Some vehicles with Blind Spot Monitoring \(BSM\) may experience the following conditions \(similar to when the BSM control modules detect dirt on the rear bumper surface\): DTC U1A4B:97 \- Radar sensor sensitivity temporarily decreases depending on various external and environmental factors \(blind spot monitoring \(BSM\) control module \(RH\)\), DTC U3000:97 \- Radar sensor sensitivity temporarily decreases depending on various external and environmental factors \(blind spot monitoring \(BSM\) control module \(LH\)\), The BSM turns ?OFF? and the BSM OFF indicator turns ?ON? in the instrument cluster while driving, The BSM will not turn on again during the drive cycle, After cycling the ignition switch off and on again, the BSM operates normally, DTC U1A4B:97 or U3000:97 is stored in memory. To correct this problem, the control logic of the BSM control modules has been changed.
- [10105653](https://open.wenmarpro.com/bulletins/10105653), 2017-06-08: SOME VEHICLES WITH BLIND SPOT MONITORING \(BSM\) MAY EXPERIENCE THE FOLLOWING CONDITIONS \(SIMILAR TO WHEN THE BSM CONTROL MODULES DETECT DIRT ON THE REAR BUMPER SURFACE\):• THE BSM TURNS “OFF” AND THE BSM OFF INDICATOR TURNS “ON” IN THE INSTRUMENT CLUSTER WHILE DRIVING • THE BSM WILL NOT TURN ON AGAIN DURING THE DRIVE CYCLE • AFTER CYCLING THE IGNITION SWITCH OFF AND ON AGAIN, THE BSM OPERATES NORMALLY • DTC U1A4B:97 OR U3000:97 IS STORED IN MEMORY \- DTC U1A4B:97 \- RADAR SENSOR SENSITIVITY TEMPORARILY DECREASES DEPENDING ON VARIOUS EXTERNAL AND ENVIRONMENTAL FACTORS \(BLIND SPOT MONITORING \(BSM\) CONTROL MODULE \(RH\)\) \- DTC U3000:97 \- RADAR SENSOR SENSITIVITY TEMPORARILY DECREASES DEPENDING ON VARIOUS EXTERNAL AND ENVIRONMENTAL FACTORS \(BLIND SPOT MONITORING \(BSM\) CONTROL MODULE \(LH\)\) TO CORRECT THIS PROBLEM, THE CONTROL LOGIC OF THE BSM CONTROL MODULES HAS BEEN CHANGED.
- [10076693](https://open.wenmarpro.com/bulletins/10076693), 2016-07-14: BSM OFF INDICATOR ON WITH DTC U1A4B:97 OR U3000:97. SOME VEHICLES WITH BLIND SPOT MONITORING \(BSM\) MAY EXPERIENCE THE FOLLOWING CONDITIONS \(SIMILAR TO WHEN THE BSM CONTROL MODULES DETECT DIRT ON REAR BUMPERS SURFACE\): BSM TURNS "OFF" AND BSM OFF INDICATOR TURNS "ON" IN THE INSTRUMENT CLUSTER WHILE DRIVING; BSM WILL NOT TURN ON AGAIN DURING DRIVE CYCLE; AFTER CYCLING, IGNITION SWITCH OFF AND ON AGAIN, BSM OPERATES NORMALLY; DTC U1A4B:97 OR U3000:97 IS STORED IN MEMORY.