U0474 is a network communication code indicating that a control module has received implausible, corrupted, or otherwise invalid data from 'Restraints System Sensor D' over the in-vehicle communication bus (typically CAN). The sensor in question is part of the Supplemental Restraint System (SRS/airbag system) and its reported data cannot be validated by the receiving module, so a fault is logged.
The sensor itself (a crash, seat position, or occupant classification sensor depending on the vehicle) has produced a signal outside its valid range or has an internal fault, causing the receiving module to flag the data as invalid.
Corroded, chafed, broken, or loose pins in the harness leading to Restraints Sensor D can distort or interrupt the data stream, making the data appear invalid to the receiving module.
An open or high-resistance feed or ground circuit prevents the sensor from operating within spec, leading to implausible readings on the bus.
The airbag control module itself is malfunctioning or has stored an internal error and is transmitting invalid data downstream to other modules on the network.
A general network problem such as incorrect termination resistance, a short to power/ground on the communication circuit, or excessive bus errors can cause any module on the bus to interpret data from this sensor as invalid.
On rare occasions the module that logs U0474 has an internal problem that causes it to misinterpret otherwise valid sensor data, but this is uncommon and is normally only suspected after the sensor and wiring have been ruled out.
The vehicle will usually still drive normally, but the airbag/SRS system may be disabled and not function in a crash. It is reasonable to have the system diagnosed soon, but it is not a 'stop now' drivability fault.
Almost never. U0474 points to the restraints sensor and its wiring/circuit, not the engine or powertrain computer. Replacing the PCM is an expensive step that is very unlikely to resolve this code and is not recommended without extensive prior diagnosis.
In most cases the code will remain stored until it is cleared with a scan tool, even after the underlying fault is fixed. Many codes also require a drive cycle without the fault reappearing before the system will pass a readiness check.
Yes. Because the sensor in question is part of the restraints system, U0474 is commonly accompanied by an illuminated airbag/SRS warning light, and in some vehicles a seat belt or occupant detection warning as well.