B0074: Passenger Presence Sensor Performance

Circuit fault

What B0074 means

GM's passenger presence system uses a sensing mat in the passenger seat cushion to classify who is sitting there. That classification drives the passenger airbag on and off indicator and tells the module whether to arm that airbag at all. A performance fault means the sensor is responding but the values are outside what the system considers a plausible seating pattern.

The wet seat suffix is a specific and useful diagnosis. Liquid in the cushion foam creates conductive paths between sensing elements, which shifts the readings in a pattern GM designed the system to recognize. Anything from a spilled drink to a leaking sunroof drain to an overly enthusiastic interior shampoo can produce it.

Common causes

• Liquid spilled into the passenger seat cushion
• Water entering through a sunroof drain, a door seal, or a windshield leak
• Upholstery cleaning or detailing that soaked the cushion
• An aged or damaged sensor mat with degraded elements
• An aftermarket seat cover or cushion changing the pressure pattern on the mat
• A connector under the seat that is corroded or not fully seated

Crash data or hardware fault?

GM treats this as a performance fault on a live measurement, which puts it outside the crash data category. The system is reading the mat right now and reporting that the numbers do not fit. Crash data is the permanent entry written when airbags actually deploy, and clearing codes with a scan tool never touches it.

Does our reset clear it?

Drying the seat is the repair here, not a module reset. Once the cushion is dry and the readings come back to normal, the code clears through a standard relearn or code erase depending on the vehicle. Our mail-in reset service is for modules locked by stored crash data after a deployment, which is a different problem entirely from a wet passenger seat.

Which makes throw it

B0074 appears on Buick, Cadillac, Chevrolet, and GMC. GM uses the same passenger presence system and the same code definitions across those brands, and the 0F wet seat suffix reads identically on all of them.

What to do next

Find the water before you touch the seat hardware, because a mat replaced under an active leak fails again. Check the sunroof drains, the door seals, and the carpet under the seat. Pull the cushion and dry it completely, then recheck the system. If the fault stays after the cushion is fully dry, the sensor mat has been damaged and the cushion or mat assembly needs replacing. Related codes: B0073, B0081, 34-1X, B001E.