Mitsubishi B1a10 ((link)) May 2026

If the problem persists after a battery change and code reset, you may need to visit a dealership to register a new key ID or inspect the vehicle's wireless control module. 42B-B1A10 Keyless/KOS key 1 low battery - Mitsubishi

Internal damage to the key fob's circuitry.

Rarely, the KOS-ECU , ETACS-ECU, or WCM may be failing and misinterpreting signals. How to Fix and Clear the Code mitsubishi b1a10

Use an OBDII scanner to erase the code from the vehicle's memory.

Ensure your keys are stored far enough away from the car when parked to prevent "parasitic" drain. If the problem persists after a battery change

Storing the key fob too close to the vehicle (within 25 feet) for extended periods can drain the battery as it constantly communicates with the KOS.

This solves the issue in the vast majority of cases. Use a high-quality replacement battery and ensure the contacts are clean. How to Fix and Clear the Code Use

While a dying battery is the most common culprit, several factors can trigger this fault:

The ECU "judges" the battery as abnormal if it receives a low voltage signal from the transmitter . If you have a second key fob experiencing the same issue, you would likely see code B1A11 . Primary Causes of B1A10

In Mitsubishi's electronic management system, every registered key fob is assigned a number. Code B1A10 corresponds to the registered with the KOS-ECU.