B1644 Code: Meaning, Symptoms, Causes & Fix

Overview

Code B1644 indicates a fault in Mirror Passenger Right Circuit Open, typically within body electronics and comfort modules.

Symptoms

battery draw complaints
related warning lamp illuminated
module resets or glitches

Common causes

Broken terminal inside harness affecting mirror passenger right circuit open
Disconnected or loose connector
Connector pin damage/corrosion or harness stress near related components

How to diagnose B1644

Confirm B1644 and capture freeze-frame data with a professional scan tool.
Inspect wiring, connectors, and grounds related to mirror passenger right circuit open for obvious defects.
Use a continuity test from module pin to component to identify opens/high resistance.
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 B1644

Moderate: This code is moderate severity: the vehicle may still operate, but fault progression can increase repair cost over time.

Can you drive with B1644?

Most vehicles can be driven short-term with B1644, but postpone heavy load/highway driving until repaired.

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 (open) in the mirror passenger right circuit open circuit/system.
Apply the required relearn/adaptation procedure if specified by service information.
Road-test and verify B1644 remains cleared under the conditions that originally set the code.

Fix options

Repair open circuit and secure connector lock.
Restore continuity and verify pin tension.
Clear DTCs and verify with live data and completed drive cycle.

Typical repair cost

$160-$850

Common mistakes when diagnosing B1644

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.

B1644 in common vehicles

B1644 appears across makes such as Mazda, Subaru, Lexus, Jeep. Failure patterns differ by platform: wiring routes, software calibration, and component supplier revisions can change root cause.

Frequently asked questions

What causes B1644?

B1644 is commonly set by open faults affecting mirror passenger right circuit open.

How much does it cost to fix B1644?

For B1644, repair costs are typically $160-$850 depending on exact root cause, labor rates, and part quality.

Can I clear B1644 without repair?

You can clear B1644 temporarily, but the code usually returns until the underlying fault is corrected.