Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2001 Lexus IS 300FACTORY OEM SERVICE PROCEDURE
Multiplex Control DTCS
MULTIPLEX DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION
| DTC | Description |
|---|---|
| B1211/11 | Power Window Master Switch ECU Communication Stop |
| B1214/14 & B1215/15 | Communication Bus Malfunction (B+ Short) Or Communication Bus Malfunction (Ground Short) |
| B1241/41 | Power Window Master Switch ECU Switch Circuit Diagnosis |
| B1242/42 | Wireless Door Lock Tuner Circuit Malfunction |
| B1244/44 | Light Sensor Circuit Malfunction |
| B1261/61 | ECM Communication Stop |
| B1262/62 | A/C ECU Communication Stop |
| B1269/69 | Theft Deterrent ECU Communication Stop |
| B1271/71 | Combination Meter ECU Communication Stop |
Factory Service Tools
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
Comes to youSame-day available12-month warranty
Get a Free QuoteNo obligation. See pricing before you book.