B1871 Code: Meaning, Symptoms, Causes & Fix

Overview

B1871 is triggered when monitoring logic identifies an issue with Passenger Air Bag Disable Module Fault affecting module-to-module CAN communication.

Symptoms

intermittent no-start or limp mode
module not responding in scan tool
feature communication timeout

Common causes

Control module logic or calibration issue affecting passenger air bag disable module fault
Component failure in the monitored system
Connector pin damage/corrosion or harness stress near related components

How to diagnose B1871

Confirm B1871 and capture freeze-frame data with a professional scan tool.
Inspect wiring, connectors, and grounds related to passenger air bag disable module fault for obvious defects.
Use freeze-frame and live data to isolate whether the issue is electrical, mechanical, or control logic.
Check for related DTCs to identify the root-cause chain before replacing parts.
After repair, clear codes and confirm readiness monitors complete without recurrence.

Severity of code B1871

Low: This code is low to moderate severity in most cases, but diagnosis is still recommended to avoid recurring warnings.

Can you drive with B1871?

The vehicle is often drivable with B1871, but plan a repair window to prevent repeat faults.

If the warning lamp is flashing or drivability/safety is affected, avoid driving and diagnose immediately.

How to fix it (step-by-step)

Repair obvious wiring/connector faults first to prevent repeat parts replacement.
Address the root fault mode (generic) in the passenger air bag disable module fault circuit/system.
Apply the required relearn/adaptation procedure if specified by service information.
Road-test and verify B1871 remains cleared under the conditions that originally set the code.

Fix options

Inspect circuit and connector condition.
Clear code and confirm through drive cycle.
Clear DTCs and verify with live data and completed drive cycle.

Typical repair cost

$160-$600

Common mistakes when diagnosing B1871

Replacing parts without verifying voltage, ground, and signal integrity first.
Ignoring related stored/pending codes that indicate upstream faults.
Skipping post-repair verification drive cycle and readiness checks.

B1871 in common vehicles

B1871 appears across makes such as Nissan, Hyundai, Kia, Volkswagen. Failure patterns differ by platform: wiring routes, software calibration, and component supplier revisions can change root cause.

Frequently asked questions

What causes B1871?

B1871 is commonly set by generic faults affecting passenger air bag disable module fault.

How much does it cost to fix B1871?

For B1871, repair costs are typically $160-$600 depending on exact root cause, labor rates, and part quality.

Can I clear B1871 without repair?

You can clear B1871 temporarily, but the code usually returns until the underlying fault is corrected.