42-2X: Right Front Impact Sensor Failure

Hardware fault

What 42-2X means

Up front, on the passenger side, a small accelerometer watches for the deceleration pattern of a frontal crash. It reports to the SRS unit continuously and runs a self test as part of that reporting. A failed self test produces 42-2X, and the module responds by disabling deployment, because it can no longer rely on one of the inputs it uses to make the call.

The location is doing most of the damage here. Front sensors mount near the radiator support, low and forward, where they take road spray, salt, heat off the engine, and vibration for the entire life of the car. Any front-end contact firm enough to move the bracket gets to the sensor as well, even when the bumper cover looks fine.

Common causes

• Corrosion inside the sensor housing after moisture worked past the seal
• Deformed mounting bracket from a low-speed front-end impact
• A sensor that was not replaced during a previous collision repair
• Heat and vibration damage to the internal electronics over many years
• Connector damage during radiator, condenser, or bumper cover service

Crash data or hardware fault?

This is the sensor reporting its own condition in real time. It is not a crash record. A crash record is written into the control module at the moment airbags deploy and stays there until the module is reset on a bench, which no amount of parts replacement will change.

Does our reset clear it?

Clearing 42-2X will not repair the sensor, and the code returns as soon as the SRS unit polls it again. The sensor is the part. Our mail-in reset is for a control module that fired and is locked on stored crash data, and that service is done after all the sensors and hardware on the car have been sorted out.

Which makes throw it

42-2X appears on the Acura side of our lookup. If you are diagnosing a Honda, confirm the number against the Honda index first so you are chasing the right sensor.

What to do next

Get the sensor in your hands before ordering parts. Check the connector for green corrosion and the housing for cracks, then confirm the bracket is flat and the fastener is torqued, because a loose sensor gives the module readings it does not expect. When the mounting and connector are good and the code persists, install a genuine OEM right front impact sensor, which we stock for Acura. Related codes: 41-2X, 43-1X, B1BAA.