B0084: Right Front Impact Sensor

Hardware fault

What B0084 means

A front impact sensor is an accelerometer mounted on the radiator support, the front frame rail, or a similar structure on the right side. It detects deceleration before the module in the passenger compartment can feel it, which gives the system more time to make a deployment decision. When the sensor fails its checks or stops reporting correctly, GM stores B0084.

Mounting does more here than hold the sensor in place, because it is part of how the sensor works. The bolted joint transmits body movement into the sensor, so a loose fastener, a shim of undercoating, or a bracket bent in a previous repair all change what the sensor feels. The module cannot tell a mis-mounted sensor from a failing one, and it flags both.

Common causes

• A sensor loosened or left unbolted after front end repair or radiator work
• Corrosion at the sensor connector from road spray, salt, and standing water
• Front collision damage that bent the bracket or stressed the sensor
• An internal failure of the sensor after years of heat and vibration
• A replacement sensor that does not match the factory part for the vehicle
• Rodent or debris damage to the front harness

Crash data or hardware fault?

GM classifies B0084 as a hardware fault, meaning the module is pointing at the sensor as a part rather than at a simple open or short in the wire. It is still not crash data. Crash data is the permanent record written when airbags deploy, protected against scan tool erasure, while a hardware fault reflects a component's current condition and clears when the part is right.

Does our reset clear it?

Replacing or remounting the sensor is what fixes a live B0084, since a reset leaves the same faulty part reporting the same thing. Where the vehicle was in a frontal collision, the front sensors often need replacing and the module will be locked with crash data at the same time. Mail us the module once the repairs are done and we clear that stored record.

Which makes throw it

B0084 is used by Buick, Cadillac, Chevrolet, and GMC. GM's shared restraint diagnostics mean the code carries the same meaning across all four brands and across the platforms that use front mounted impact sensors.

What to do next

Check the mounting bolt and the connector before ordering a sensor, because a loose fastener or a corroded plug explains a good share of these without the sensor being bad. Make sure the sensor sits flat against clean bare metal. If the mount and wiring are sound and the fault stays, replace the sensor with a genuine OEM unit, and we can source one and check your module at the same time. Related codes: B0083, B0085, 01639, B0020.