AutoCodes – Buick – B1340 Buick

B1340 Buick Code - Left Air Temperature Actuator

Quick Answer

The Instrument Panel Module (IPM) controls the HVAC door actuators to regulate the airflow through the Heating, Ventilation, and Air Conditioning (HVAC) system. Common causes include Faulty Left Air Temperature Actuator, Left Air Temperature Actuator harness is open or shorted, Left Air Temperature Actuator 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: B1340 Buick indicates Left Air Temperature Actuator.
Common causes: Common causes include Faulty Left Air Temperature Actuator, Left Air Temperature Actuator harness is open or shorted, Left Air Temperature Actuator 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 1,275

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 Mar 14, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B1340 Buick Description

The Instrument Panel Module (IPM) controls the HVAC door actuators to regulate the airflow through the Heating, Ventilation, and Air Conditioning (HVAC) system. Each actuator is a 5-wire bi-directional electric motor that incorporates a feedback potentiometer. Ignition 3 voltage, low reference, control, 5-volt reference and position signal circuits enable the actuator to operate. The control circuit uses either a 0, 2.5, or 5-volt signal to command the actuator movement. When the actuator is at rest, the control circuit value is 2.5 volts. A 0 or 5-volt control signal commands the actuator movement in opposite directions. When the actuator shaft rotates, the potentiometer's adjustable contact changes the door position signal between 0-5 volts. The IPM converts the voltage values to count values where one volt is approximately equal to 51 counts. The IPM uses a range of 0-255 counts to index the actuator position. The door position signal voltage is converted to a 0-255 count range. When the module sets a commanded, or targeted value, the control signal is changed to either 0 or 5 volts depending upon the direction that the actuator needs to rotate to reach the commanded value. As the actuator shaft rotates the changing position signal is sent to the module. Once the position signal and the commanded value are the same, the module changes the control signal to 2.5 volts.

OBDII Code B1340 Buick - Left Air Temperature Actuator - AutoCodes.com — B1340 Buick Code - Left Air Temperature Actuator

What does this mean?

What are the Possible Causes of the DTC B1340 Buick?

Faulty Left Air Temperature Actuator
Left Air Temperature Actuator harness is open or shorted
Left Air Temperature Actuator circuit poor electrical connection
Faulty Instrument Panel Module (IPM)

How to Fix the DTC B1340 Buick?

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 B1340 Buick 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.

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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 B1340 Buick Code

1. What does the OBDII code B1340 mean on a Buick?

It indicates a malfunction in the left air temperature actuator, responsible for controlling the temperature blend door on the driver's side of the HVAC system.

2. What are the symptoms of code B1340 in a Buick?

Common symptoms include inconsistent or incorrect temperature control on the driver's side and unusual clicking or tapping noises from the HVAC system.

3. What causes the B1340 code to appear?

The code is usually caused by a faulty left air temperature actuator, wiring issues, or problems with the HVAC control module.

4. How do I diagnose the B1340 code?

Start by checking for clicking sounds from the actuator, inspecting the wiring for damage, and testing the actuator's functionality using a diagnostic scan tool.

5. Can I drive my Buick with the B1340 code?

Yes, the vehicle is safe to drive, but the HVAC system may not function properly on the driver's side, leading to discomfort.

6. How do I fix the B1340 code on my Buick?

Repairs often involve replacing the left air temperature actuator, but you should also inspect and repair any damaged wiring or connectors.

7. How much does it cost to fix the B1340 code?

Replacing the left air temperature actuator typically costs between $150 and $300, including parts and labor, depending on the vehicle model and labor rates.

8. Can a faulty HVAC control module cause the B1340 code?

Yes, though it is less common, a malfunctioning HVAC control module can prevent proper communication with the actuator, triggering the code.

9. How can I reset the B1340 code after making repairs?

Use an OBDII scan tool to clear the code after repairs or disconnect the battery for a few minutes, but only if the underlying issue has been resolved.

10. How can I prevent the B1340 code from recurring?

Regularly inspect your vehicle's HVAC system, address unusual noises promptly, and ensure wiring and connectors are free of corrosion or damage.