AutoCodes – Buick – P0155 Buick

P0155 Buick Code - HO2S Heater Performance Bank 2 Sensor 1

Quick Answer

Heated Oxygen Sensors (HO2S) are used for fuel control and post catalyst monitoring. Common causes include Faulty Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1, Heated Oxygen Sensor Bank 2 Sensor 1 harness is open shorted, Heated Oxygen Sensor Bank 2 Sensor 1 circuit poor electrical connection. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means: P0155 Buick indicates HO2S Heater Performance Bank 2 Sensor 1.
Common causes: Common causes include Faulty Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1, Heated Oxygen Sensor Bank 2 Sensor 1 harness is open shorted, Heated Oxygen Sensor Bank 2 Sensor 1 circuit poor electrical connection.
Severity: Moderate - service should be scheduled soon.
Can I drive?: The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

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Code Popularity 4,289

How popular is this code, among other codes? Low

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 23, 2024

Description
Step-by-Step Diagnostic Guide
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
Comments
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Code P0155 Buick Description

Heated Oxygen Sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach an operating temperature to provide an accurate voltage signal. A heating element inside the HO2S minimizes the time required for the sensors to reach operating temperature. Voltage is provided to the heater by an ignition voltage circuit through a fuse. With the engine running, the ground is provided to the heater by the HO2S heater low control circuit through a low side driver within the Engine Control Module (ECM). The ECM uses Pulse Width Modulation (PWM) to control the HO2S heater operation to maintain a specific HO2S operating temperature range.
The Diagnostic Trouble Code (DTC) will be set when the ECM detects that the HO2S 1 heater current is out of factory specifications.

OBDII Code P0155 Buick - HO2S Heater Performance Bank 2 Sensor 1 - AutoCodes.com — P0155 Buick Code - HO2S Heater Performance Bank 2 Sensor 1

What does this mean?

What are the Possible Causes of the DTC P0155 Buick?

Faulty Heated Oxygen Sensor (H2OS) Bank 2 Sensor 1
Heated Oxygen Sensor Bank 2 Sensor 1 harness is open shorted
Heated Oxygen Sensor Bank 2 Sensor 1 circuit poor electrical connection
Heated Oxygen Sensor Bank 2 Sensor 1 circuit fuse
Faulty Engine Control Module (ECM)

How to Fix the DTC P0155 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 does this mean?

Code Tech Notes

The code means that there is a problem with the heater element circuit of the heated oxygen sensor. The control module monitors how long it takes the sensor to warm up and start sending an adequate signal. The code is set when the sensor is taking too long to warm up. Water getting inside the heated oxygen sensor connector can cause the heated oxygen sensor fuse to blow. Before replacing the sensor, check for the condition of the heated oxygen sensor fuse and connectors. If the fuse and connector are OK, replacing the O2 Sensor usually takes care of the problem.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0155 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.