B1308 airbag control unit fault

What does error code B1308 mean in the airbag control unit?

The error code B1308 indicates a specific issue with the door latch switch, known as the TN Latch Close Sensor, in Mitsubishi vehicles. It means ‘TN latch close sensor Left OFF, Right ON’, indicating that the airbag control unit is receiving an inconsistent signal: the left door is detected as not properly closed, while the right door is reported as closed.

From an electronic standpoint, this diagnostic code points to an open circuit or an implausible value in the wiring of the left door closing sensor. The airbag control unit (ACU) continuously monitors the status of the door sensors to activate the appropriate restraint systems in the event of a side impact. If a sensor sends an erroneous signal, the system cannot function reliably and, for safety reasons, enters a fault condition signaled by the illumination of the airbag warning light.

Although the primary cause often lies externally—either in the sensor itself or its wiring—the fault may also stem from an internal defect within the airbag control unit, such as a processing error in handling input signals or a malfunction in the memory area.

What symptoms appear with error B1308?

The main symptom of error B1308 is a permanently illuminated airbag warning light on the instrument panel. This warning remains active after the engine starts and cannot be cleared by a simple reset until the underlying technical issue is resolved. Consequently, the entire airbag system is disabled or operates only in a limited capacity.

A direct and safety-critical symptom is the deactivation of the airbag system. In the event of a crash, there is a risk that the airbags will fail to deploy or deploy incorrectly, significantly increasing the risk of injury to occupants.

In some cases, diagnostic tools may be unable to establish communication with the airbag control unit, or communication may be disrupted, especially if the fault originates from an internal problem within the control unit.

What causes error code B1308?

The most common cause of error B1308 is a defect in the peripheral components of the control unit. These include a dirty or faulty door latch sensor on the driver’s side, corroded connectors, or a broken wire in the supply line. An improper voltage supply to the sensor can also trigger the error. Less frequently, the issue arises from an internal software or memory fault within the airbag control unit itself.

A defective or mechanically jammed door latch sensor (Latch Close Sensor) on the driver’s side is the primary source of the problem. Wear, dirt, or moisture can cause the sensor to send incorrect signals to the control unit.

Poor electrical connections are another frequent cause. Damage to the wiring harness, particularly around the door penetration, along with corrosion at the connector contacts, can lead to signal loss or implausible readings.

In some instances, the airbag control unit itself is at fault. An internal hardware defect—especially in the memory area (EEPROM)—or a processing error in handling sensor data can generate error code B1308. Often, additional error codes accompany it, such as B1309 (timeout error), B1150 (no communication), B1157 (crash signal stored), or B1170 (EEPROM memory function faulty).

On which vehicles does error B1308 occur?

Error code B1308 is specific to Mitsubishi vehicles. It appears across various model series and production years where this generation of airbag control units was installed. Affected models include sedans, SUVs, and commercial vehicles from the manufacturer.

At Airbag24, we repair error code B1308 for the following Mitsubishi models:

Mitsubishi Mirage CA

Mitsubishi Lancer CZ and Lancer Evolution VI

Mitsubishi Pajero Sport K90 (1996–2008)

Mitsubishi L200 K74 and L200 KJ (2015–2023)

Mitsubishi Xpander Cross A05A

How is error B1308 repaired?

The repair focuses on eliminating the root cause. Following diagnosis, the airbag control unit is removed and sent to a specialist for analysis. At Airbag24, we inspect the electronic components, clear any errors stored in memory, and—if necessary—erase crash data, fully restoring the device.

The process at Airbag24 is designed for efficiency and safety. After removing the control unit from the vehicle—typically located in the center console or beneath one of the front seats—you send it to us. Our technicians conduct a comprehensive chip-level analysis to pinpoint the exact source of the fault.

Subsequently, professional repair is carried out. This includes testing and refurbishing the electronic components, as well as safely erasing all fault codes and any stored crash data. The control unit is then thoroughly tested to ensure full functionality.

Following successful repair and final inspection, the control unit is shipped back to you. It is typically ready for immediate installation (plug-and-play) and does not require re-coding. We provide 2 years' statutory liability for defects on all repairs.