Airbag control unit with part number Y851M-EH100

What is the function of the airbag control unit Y851M-EH100?

The airbag control unit Y851M-EH100 is the central safety module for the Infiniti M45 of the Y50 series. It processes data from acceleration and yaw rate sensors in real time to precisely deploy airbags and seatbelt pretensioners at the right moment during a crash, thereby protecting occupants.

As the ECU (Electronic Control Unit) of the restraint system, it is an indispensable component for vehicle safety. It continuously monitors all connected components—such as sensors, airbag modules, and seatbelt pretensioners—for proper functionality.

This control unit is specifically designed for the Infiniti M45 Y50 models (model years 2005–2010) and the Infiniti Premium M45.

There are also alternative compatible part numbers that belong to the same control unit family. These include K851M-EH001, Y851M-EH001, and K851M-EH100, which are technically equivalent.

What defects occur in the Y851M-EH100?

The most common causes of failure for the Y851M-EH100 are stored crash data after an accident, which locks the control unit, as well as severe internal hardware faults often indicated by error code B1239. Other defects include communication issues with diagnostic tools and damage caused by water ingress.

After a crash, the control unit stores so‑called crash data. This information prevents further operation of the device, even if no external damage is visible. The airbag warning light remains illuminated until this data is professionally erased.

A critical defect is an internal electronic failure. Diagnostic tools frequently read error codes B1000 or B1239; B1239 indicates a serious internal problem requiring repair at the component level.

Another frequent issue is complete loss of communication. In such cases, the workshop can no longer establish a connection to the airbag control unit via the OBD interface, making diagnosis and troubleshooting on the vehicle impossible.

External factors like moisture or water damage can also harm the sensitive electronics inside the control unit, leading to malfunctions or total failure.

How do you recognize a defect in the Y851M-EH100?

A defective Y851M-EH100 control unit typically manifests as a permanently or intermittently illuminated airbag warning light on the dashboard. Additionally, diagnostic tools may fail to connect to the control unit, or specific error codes such as B1239 may be displayed, indicating an internal fault.

The clearest sign of a problem in the airbag system is the activated airbag warning light. Do not ignore this warning, as the protective function of the airbags will no longer be guaranteed in an emergency.

If the service center determines that communication with the control unit is impossible, there is strong suspicion of an internal defect within the unit itself.

A thorough diagnosis before removing the control unit is essential. The workshop should verify whether the fault truly lies within the control unit or is caused by other vehicle components, such as faulty sensors, cables, or connectors. This helps avoid unnecessary expenses.

In which vehicles is the Y851M-EH100 installed?

The airbag control unit with part number Y851M-EH100, along with its compatible variants, is found exclusively in Infiniti vehicles. At Airbag24, we primarily repair this control unit for the Infiniti M45 model line of the Y50 generation.

At Airbag24, we have extensive experience repairing this control unit for the following specific models:

Infiniti M45 (Y50 series, model years 2005–2010)

Infiniti Premium M45

How does the repair of the Y851M-EH100 proceed?

Upon receipt of the removed control unit at Airbag24, our technicians perform a systematic diagnosis to identify the exact source of the fault. This is followed by professional repair, which may involve erasing crash data or replacing defective electronic components. A final test ensures full functionality.

The repair process at Airbag24 follows a proven, structured procedure. First, the control unit undergoes an initial inspection to verify the symptoms described by the customer.

In the next step, experienced mechatronics engineers address the identified defect. This may include clearing crash data, repairing processors or memory chips, or fixing cold solder joints.

Following successful repair, each control unit undergoes a comprehensive functional test on specialized test benches. This ensures the device operates flawlessly, just like a new component.

Should a repair prove impossible in rare cases, we often offer remanufactured replacement units as an alternative. We provide a 12-month warranty on every repaired unit.

What shipping options are available at Airbag24?

To have your Y851M-EH100 control unit repaired, you can either send it to Airbag24 securely packaged at no cost, or conveniently arrange for UPS to pick it up from your preferred location. After repair, we’ll return the unit free of charge via standard UPS shipping; express shipping options are available for an additional fee.

For the outbound shipment, you have two convenient choices: pack the defective control unit safely and take it to the post office yourself, or book UPS’s pickup service, which will collect the package directly from your home or workshop.

The return shipment of the repaired control unit is, by default, free of charge via reliable standard UPS shipping.

For an even faster return, we also offer UPS express shipping. Both shipping methods can, if desired, be arranged with cash-on-delivery. Of course, personal collection at our premises is also possible.