AutoCodes – Generic – B2126

B2126 Code - Detention Switch

Quick Answer

Detention switch is installed on Automatic Transmission (AT) device. Common causes include Faulty Detention Switch, Detention Switch harness is open or shorted, Detention Switch 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: B2126 indicates Detention Switch.
Common causes: Common causes include Faulty Detention Switch, Detention Switch harness is open or shorted, Detention Switch 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 3,421

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Sep 19, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B2126 Description

Detention switch is installed on Automatic Transmission (AT) device. It is turned OFF when the AT selector lever is in Park (P) position. The driver seat control unit judges that the AT selector lever is in P position if continuity does not exist in this circuit.

OBDII Code B2126 - Detention Switch - AutoCodes.com — B2126 Code - Detention Switch

What does this mean?

What are the Possible Causes of the DTC B2126?

Faulty Detention Switch
Detention Switch harness is open or shorted
Detention Switch circuit poor electrical connection

How to Fix the DTC B2126?

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 B2126 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 B2126 code?

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Need Help with the Code?

Get the B2126 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

B2126 Chrysler — Sensor Supply Voltage Low
B2126 Dodge — Sensor Supply Voltage Low
B2126 Infiniti — Detention Switch
B2126 Jeep — Sensor Supply Voltage Low
B2126 Nissan — Detention Switch
B2126 RAM — Sensor Supply Voltage Low

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 B2126 Code

1. What does the OBDII code B2126 mean?

B2126 refers to an issue with the detention (or door ajar) switch, indicating it may be malfunctioning or stuck in an open or closed position.

2. What are the common symptoms of a B2126 code?

Symptoms may include the door ajar warning light staying on, interior dome lights not turning off, or issues with the vehicleâ€™s alarm system.

3. What causes the B2126 code to appear?

The code is typically triggered by a faulty detention switch, damaged wiring, corroded connectors, or a malfunction in the door latch mechanism.

4. Can a B2126 code affect my vehicle's performance?

While it wonâ€™t directly affect engine performance, it can cause electrical issues like battery drain due to lights staying on or prevent the alarm from functioning properly.

5. How do I diagnose a B2126 code?

Start by checking the detention switch and door latch for visible damage, inspect wiring and connectors for corrosion or breaks, and use a multimeter to test electrical continuity.

6. Can I fix the B2126 code myself?

If youâ€™re comfortable, you can clean or replace the detention switch, repair damaged wiring, or clean corroded connectors. Otherwise, consult a professional mechanic.

7. How much does it cost to repair a B2126 code?

The repair cost depends on the issue. Replacing a detention switch typically costs $50â€“$150, excluding labor, while wiring repairs might vary.

8. Can a B2126 code cause my battery to drain?

Yes, if the detention switch causes interior lights to stay on, it can lead to battery drainage over time.

9. Is it safe to drive with a B2126 code?

Itâ€™s generally safe to drive, but you may experience electrical inconveniences like false alarms or lights staying on, which should be addressed soon.

10. How can I prevent a B2126 code from recurring?

Regular maintenance, such as cleaning door latch mechanisms and inspecting wiring for wear, can help prevent this issue from reoccurring.