AutoCodes – Generic – B277B

B277B Code - HVAC LIN Communication

Quick Answer

A Positive Temperature Coefficient (PTC) heater is used as the heat source for heating. Common causes include Faulty Positive Temperature Coefficient (PTC) Heater, PTC Heater harness is open or shorted, PTC Heater 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: B277B indicates HVAC LIN Communication.
Common causes: Common causes include Faulty Positive Temperature Coefficient (PTC) Heater, PTC Heater harness is open or shorted, PTC Heater 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 794

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 Feb 04, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B277B Description

A Positive Temperature Coefficient (PTC) heater is used as the heat source for heating. The PTC is a ceramic material with barium titanate as the primary component. The PTC heater provides an internal control circuit and performs Local Interconnect Network (LIN) communication with A/C Auto Amplifier. Based on the signals from A/C Auto Amplifier, the microcomputer inside PTC heater controls the heater output by PWM. When current is applied, it heats up. Upon reaching a certain temperature (Curie temperature) the resistance suddenly increases, limiting the current, and maintaining a constant amount of heating. The Diagnostic Trouble Code (DTC) sets when there is an error in the signal send from the A/C Auto Amplifier.

OBDII Code B277B - HVAC LIN Communication - AutoCodes.com — B277B Code - HVAC LIN Communication

What does this mean?

What are the Possible Causes of the DTC B277B?

Faulty Positive Temperature Coefficient (PTC) Heater
PTC Heater harness is open or shorted
PTC Heater circuit poor electrical connection
Faulty A/C Auto Amplifier

How to Fix the DTC B277B?

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 B277B 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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Need Help with the Code?

Get the B277B code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

B277B Nissan — HVAC LIN Communication

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 B277B Code

1. What does the OBDII code B277B mean?

The B277B code indicates an issue with the HVAC LIN (Local Interconnect Network) communication, where the system detects a fault in the data exchange between HVAC control modules.

2. What are common symptoms of the B277B code?

Symptoms may include malfunctioning HVAC controls, unresponsive temperature or fan settings, or the climate control system failing to operate properly.

3. What causes the B277B code to appear?

Common causes include a faulty HVAC control module, wiring issues such as damaged or corroded connectors, or a broken LIN bus communication line.

4. Can I drive with the B277B code active?

Yes, you can usually drive with this code active, but your HVAC system might not function correctly, affecting cabin comfort.

5. How is the B277B code diagnosed?

A technician will use a scan tool to verify the code, inspect the LIN bus wiring and connections, and test the HVAC control modules for proper functionality.

6. What are possible repairs for the B277B code?

Repairs might include replacing a faulty HVAC control module, repairing or replacing damaged wiring, or cleaning corroded connectors in the LIN communication circuit.

7. Can a weak battery cause the B277B code?

Yes, a weak or failing battery can cause communication issues on the LIN bus, potentially triggering the B277B code.

8. How much does it cost to fix the B277B code?

Repair costs vary depending on the issue but may range from $100 to $500, with higher costs for module replacement.

9. Can I fix the B277B code myself?

If youâ€™re experienced with automotive electrical systems, you can check for loose connections or damaged wiring, but more complex issues may require professional assistance.

10. Will clearing the code solve the problem?

Clearing the code may temporarily remove it, but if the underlying issue isnâ€™t fixed, the code will likely reappear.