Airbag control unit with part number A1698207726

What is the function of the airbag control unit A1698207726?

The airbag control unit with part number A1698207726 is the central control module for the entire occupant safety system (SRS) in the Mercedes-Benz A-Class (W169) and B-Class (W245). Manufactured by TRW, this module processes data from the acceleration sensors and determines, in the event of a crash, whether and which airbags and seatbelt pretensioners should be deployed.

As the brain of the passive safety system, it continuously monitors vehicle dynamics. Inside the control unit are precision acceleration and deceleration sensors that reliably detect a collision. When predefined threshold values are exceeded, the unit sends ignition signals within milliseconds to the appropriate pyrotechnic components—such as front, side, and, if applicable, knee airbags—as well as to the seatbelt pretensioners.

At the same time, the control unit stores all relevant crash-related data and internal system errors, which are crucial for diagnostics and accident analysis.

Why does the control unit A1698207726 fail? Typical defects and causes

The most common reason for failure of the control unit A1698207726 is permanently stored crash data following an accident, which locks the unit at the software level. In addition, internal hardware defects on the circuit board—such as faulty memory chips (EEPROM/Flash), defective sensors, or failed voltage regulators—can lead to complete failure.

After an airbag deployment, the manufacturer blocks the control unit from being reused. However, specialized workshops can electronically reset these crash data, restoring full functionality to the unit. This is a proven and cost-effective alternative to purchasing a new part, especially for the B-Class W245.

Another frequent issue involves defects in the memory ICs (EEPROM/Flash). Data corruption or a hardware fault in the chip results in internal errors that are often logged in the fault memory as “control unit defective” (e.g., B1111, B9111) and cannot be cleared.

The peripheral electronics on the circuit board can also fail. Faulty CAN transceivers cause a complete loss of communication, while malfunctions in the internal sensor system or power supply can render the unit inoperable. The entire family of control units—including numbers A1698206626 and A1698206726—is known for these types of electronic failures.

How do you recognize a defect in the airbag control unit A1698207726?

A defect in the control unit A1698207726 primarily manifests as the airbag warning light (SRS) remaining constantly illuminated in the instrument cluster. Additionally, error codes such as “control unit defective” or “crash data stored” cannot be cleared, or communication with the diagnostic tool becomes impossible altogether.

The most noticeable symptom is the active SRS warning light, which fails to turn off after starting the vehicle. This indicates a serious fault in the restraint system that compromises passenger safety.

When diagnosed using workshop test tools (e.g., Mercedes Star Diagnosis, Bosch KTS), error codes like B1111, B9111, or B119C are read out. These directly point to an internal defect or stored crash data. Attempts to clear these errors fail because the root cause lies within the unit itself.

Another clear sign is a complete breakdown in communication: the control unit no longer responds to requests from the diagnostic device, making further troubleshooting inside the vehicle impossible.

In some cases, messages such as “communication failure with the airbag control unit” or “control unit incorrectly coded” appear. These often indicate not just a software or coding issue, but rather symptoms of a deeper electronic fault within the control unit.

In which vehicles is the control unit A1698207726 installed?

The TRW airbag control unit A1698207726 is mainly used in the Mercedes-Benz B-Class of the W245 series (circa 2005–2011). According to parts catalogs, this module is also fitted in the technically related A-Class of the W169 series.

At Airbag24, we repair the control unit A1698207726 for the following models:

Mercedes-Benz B-Class (W245 series, Sports Tourer), model years circa 2005 to 2011, including the B 180 CDI.

Mercedes-Benz A-Class (W169 series), model years circa 2004 to 2012.

How is the control unit A1698207726 professionally repaired?

Upon receipt at Airbag24, the control unit undergoes a detailed electronic analysis down to the component level. The repair process includes targeted deletion of stored crash data (reset), repair or replacement of faulty memory chips (EEPROM/Flash), and other affected components. A final functional test ensures full operational capability.

The repair process at Airbag24 is tailored to address the specific weaknesses of this TRW control unit. First, an initial diagnostic check is performed to test communication and inspect the circuit board for visible damage.

The core of the refurbishment lies in data repair. Using specialized programming tools, direct access is gained to the memory chip (EEPROM/Flash) to remove the crash lockout and restore the software structure, ensuring the control unit functions like a brand-new component.

If a hardware defect is present, faulty components such as voltage regulators, communication ICs, or memory chips are carefully identified, desoldered, and replaced with new, high-quality parts.

Subsequently, each repaired control unit undergoes testing on a dedicated test bench to guarantee flawless communication and proper operation of all internal circuits. You receive a 12-month warranty on the completed repair.

What shipping options are available at Airbag24?

You can either ship your control unit to Airbag24 yourself at no cost or arrange a convenient UPS pickup. For returns, we offer free standard UPS shipping as well as various express and cash-on-delivery options. Personal collection is also available.

Shipping to us: Simply mail your removed control unit to us, or take advantage of our convenient UPS pickup service, where a courier collects the package directly from your location.

Returning to you: We provide several return methods. Standard UPS shipping is free of charge; if you need faster delivery, you can opt for UPS Express shipping.

Cash-on-delivery: Both standard and express shipping can be arranged as cash-on-delivery services upon request, allowing you to pay for the repair conveniently and securely directly to the courier.

Self-collection: Once repaired, you may also pick up your control unit in person at our facility.