43-2X: Left Side Impact Sensor Failure

Hardware fault

What 43-2X means

Side impact sensors do more than pass along a reading. Each one runs a self test and tells the control module the result, which is how a failed sensor gets identified without any wiring fault. A failure report from the first left side sensor stores 43-2X, and the SRS unit stops trusting the side deployment decision on that side of the car.

Because the module is still hearing from the sensor, the wiring is doing its job. The problem lives inside the housing. Sensors in the lower body structure sit close to the floor, the sill, and the door opening, which means years of temperature swings, vibration, and occasional moisture reach them even when nothing looks wrong from the outside.

Common causes

• Moisture that worked past the sensor seal and attacked the internal electronics
• Vibration and thermal cycling fatiguing the sensor over a long service life
• A sensor reused after a prior side impact repair rather than replaced
• Physical shock from a door or sill repair transmitted through the mounting bracket
• A sensor mounted on a bracket that was bent or not fully tightened

Crash data or hardware fault?

43-2X is a hardware self test result reported live, not a stored crash record. It disappears once a working sensor is installed. Deployment data is permanent by design, written into the control module the moment the system fires, and it takes a bench reset rather than a repair to remove it.

Does our reset clear it?

Clearing this code does not repair anything inside the sensor. The module asks again, gets the same answer, and stores 43-2X. Replace the sensor. If the car was in a side impact and the control module is also locked on crash data, that part is what our mail-in reset handles once the sensors and bags have been replaced.

Which makes throw it

Our Acura index carries 43-2X for the first left side impact sensor. Check the number against the list that matches the car so you are replacing the sensor the code actually names.

What to do next

Confirm you are at the right sensor before you buy one, since the left side can carry more than one sensor and the code names the first. Inspect the housing and the connector for corrosion and cracking, and check that the bracket is flat against the body and the fastener is tight. When the mounting is good and the failure report stays, install a genuine OEM Acura side impact sensor. Related codes: 43-1X, 44-1X, B1620.