AutoCodes – Generic – C2309

C2309 Code - Open In B+ Circuit

Quick Answer

Battery voltage will be applied to the +B terminal when the power switch is turned on (IG). Common causes include Faulty Transmission Control ECU Assembly, Transmission Control ECU harness is open or shorted, Transmission Control ECU 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: C2309 indicates Open In B+ Circuit.
Common causes: Common causes include Faulty Transmission Control ECU Assembly, Transmission Control ECU harness is open or shorted, Transmission Control ECU 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 4,351

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 Jun 14, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code C2309 Description

Battery voltage will be applied to the +B terminal when the power switch is turned on (IG). When a +B terminal voltage malfunction is detected, the Transmission Control ECU outputs this Diagnostic Trouble Code (DTC).

OBDII Code C2309 - Open In B+ Circuit - AutoCodes.com — C2309 Code - Open In B+ Circuit

What does this mean?

What are the Possible Causes of the DTC C2309?

Faulty Transmission Control ECU Assembly
Transmission Control ECU harness is open or shorted
Transmission Control ECU circuit poor electrical connection
Faulty Auxiliary Battery

How to Fix the DTC C2309?

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 C2309 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 C2309 code?

Need more information on how to fix the C2309 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the C2309 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

C2309 Lexus — Open In B+ Circuit
C2309 Toyota — Open In B+ Circuit

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 C2309 Code

1. What are the common symptoms of OBDII code C2309 (Open In B+ Circuit)?

The common symptoms include illuminated Check Engine Light (CEL), rough idle, poor engine performance, and difficulty starting the vehicle.

2. What does "Open In B+ Circuit" mean in relation to OBDII code C2309?

"Open In B+ Circuit" indicates that there is a break or interruption in the positive battery voltage circuit, causing a loss of power to a particular component or system in the vehicle.

3. What are the possible causes of OBDII code C2309?

Possible causes include damaged wiring in the B+ circuit, a faulty battery, loose or corroded battery terminals, a blown fuse, or a malfunctioning alternator.

4. How can I diagnose the issue related to OBDII code C2309 at home?

You can start by checking the battery and its connections for any visible damage or corrosion. Inspect the wiring in the B+ circuit for breaks or fraying. Use a multimeter to test for continuity in the circuit.

5. Is it safe to continue driving with OBDII code C2309 present?

It is not recommended to drive with this code present, as the underlying issue could lead to further electrical problems or potential stalling of the vehicle.

6. Can I reset the OBDII code C2309 by disconnecting the battery?

While disconnecting the battery may clear the code temporarily, it will not fix the underlying issue causing the fault. It is advisable to diagnose and repair the problem to prevent the code from reoccurring.

7. How much does it typically cost to repair OBDII code C2309?

The cost of repair can vary depending on the underlying cause. Simple fixes like replacing a fuse or repairing a wire may cost less, while replacing a damaged alternator or battery could be more expensive.

8. Will OBDII code C2309 affect the vehicle's emissions or performance?

Yes, this code can affect the vehicle's emissions and performance, as it indicates a problem with the power supply to essential components that can impact engine operation.

9. Can extreme weather conditions cause OBDII code C2309 to trigger?

Yes, extreme weather conditions such as extreme heat or cold can potentially cause issues with the battery or wiring, leading to the triggering of OBDII code C2309.

10. How long does it usually take to repair OBDII code C2309?

The repair time can vary depending on the specific cause of the issue and the complexity of the repair. Simple fixes may take just a few hours, while more involved repairs could take longer.