AutoCodes – Saturn – B0101 Saturn

B0101 Saturn Code - Driver-Side EFS Not Okay Message

Quick Answer

Electronic Frontal Sensor (EFS), also known as a front end sensor, uses a unidirectional 2-wire circuit. Common causes include Faulty Driver-Side Electronic Frontal Sensor (EFS), Driver-Side Electronic Frontal Sensor (EFS) harness is open or shorted, Driver-Side Electronic Frontal Sensor (EFS) circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: B0101 Saturn indicates Driver-Side EFS Not Okay Message.
Common causes: Common causes include Faulty Driver-Side Electronic Frontal Sensor (EFS), Driver-Side Electronic Frontal Sensor (EFS) harness is open or shorted, Driver-Side Electronic Frontal Sensor (EFS) circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 1,058

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Jun 14, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B0101 Saturn Description

Electronic Frontal Sensor (EFS), also known as a front end sensor, uses a unidirectional 2-wire circuit. EFS sensor modulates current on the interface to send identification, State Of Health (SOH) and deployment commands to Sensing and Diagnostic Module (SDM). The SDM serves as a power source and ground for EFS. When ignition is turned on and EFS detects power from SDM, EFS responds by performing internal diagnostics and sending identification to SDM. SDM considers identification message to be valid if received within 5 seconds of EFS powering up. EFS continually communicates a status message to SDM. When fault is detected, SDM will attempt to reset EFS twice by removing and applying power. If fault is still present, SDM will set a Diagnostic Trouble Code (DTC).

OBDII Code B0101 Saturn - Driver-Side EFS Not Okay Message - AutoCodes.com — B0101 Saturn Code - Driver-Side EFS Not Okay Message

What does this mean?

What are the Possible Causes of the DTC B0101 Saturn?

Faulty Driver-Side Electronic Frontal Sensor (EFS)
Driver-Side Electronic Frontal Sensor (EFS) harness is open or shorted
Driver-Side Electronic Frontal Sensor (EFS) circuit poor electrical connection
Faulty Sensing and Diagnostic Module (SDM)

How to Fix the DTC B0101 Saturn?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B0101 Saturn code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the B0101 Saturn code?

Need more information on how to fix the B0101 Saturn code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B0101 Saturn code diagnosed by a professional: Find a repair shop in your area

Precautions for SRS “AIR BAG” and “SEAT BELT PRE-TENSIONER” Service

Never probe the electrical connectors on air bag, side air curtain modules or seat belts.
Never disassemble or tamper with safety belt buckle/retractor pretensioners, adaptive load limiting retractors, safety belt inflators, or probe the electrical connectors.
Do not use electrical test equipment to check SRS circuits unless instructed to in this Service Manual.
Before servicing the SRS, turn ignition switch OFF, disconnect both battery cables and wait at least 3 minutes. For approximately 3 minutes after the cables are removed, it is still possible for the air bag and seat belt pre-tensioner to deploy. Therefore, do not work on any SRS connectors or wires until at least 3 minutes have passed.

Failure to follow this instruction may result in the accidental deployment of these modules, which increases the risk of serious personal injury or death.

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about B0101 Saturn Code

1. What does OBDII code B0101 on a Saturn mean?

The OBDII code B0101 on a Saturn indicates a problem with the Driver-Side EFS (Electrochromic Front Sensor) Not Okay Message.

2. What are the common symptoms of a Driver-Side EFS issue related to code B0101 on a Saturn?

Common symptoms include a malfunctioning auto-dimming rearview mirror, erratic dimming behavior, or a warning message displayed on the mirror.

3. What are the possible causes of OBDII code B0101 on a Saturn?

Possible causes include a faulty driver-side EFS sensor, wiring issues, a malfunctioning auto-dimming mirror, or a problem with the vehicle's electrical system.

4. How can I diagnose the cause of OBDII code B0101 on my Saturn?

Diagnosing the issue typically involves inspecting the driver-side EFS sensor, checking the wiring for any damage, and testing the auto-dimming mirror functionality. A diagnostic scan tool can also help pinpoint the exact cause.

5. Can I repair OBDII code B0101 on my Saturn myself?

Depending on the cause of the issue, some repairs related to code B0101, such as replacing a faulty sensor or fixing wiring problems, can be done by DIY enthusiasts with the right tools and knowledge.

6. Is it safe to continue driving with OBDII code B0101 on my Saturn illuminated?

While the vehicle may still be drivable with this code, it's recommended to address the issue promptly to ensure the proper functioning of the driver-side EFS sensor and auto-dimming mirror.

7. How much does it typically cost to repair OBDII code B0101 on a Saturn?

The cost of repairing code B0101 on a Saturn can vary depending on the underlying cause of the issue, the extent of the repairs needed, and whether you choose to fix it yourself or seek professional help.

8. Can resetting the OBDII system clear code B0101 on my Saturn?

Resetting the OBDII system may temporarily clear the code, but if the underlying issue is not addressed, the code is likely to reappear. It's important to diagnose and fix the root cause of the problem.

9. Are there any recalls or technical service bulletins related to OBDII code B0101 on Saturn vehicles?

It's recommended to check with Saturn dealerships or online resources for any recalls or technical service bulletins related to code B0101 to see if your vehicle may be eligible for free repairs or assistance.

10. How can I prevent OBDII code B0101 from occurring on my Saturn in the future?

Regularly inspecting the driver-side EFS system, ensuring proper electrical connections, and addressing any issues promptly can help prevent code B0101 from occurring on your Saturn.