Engine-Codes - Buick - P0155 BUICK

P0155 BUICK - HO2S Heater Performance Bank 2 Sensor 1

Repair Importance Level: 2/3
Repair Difficulty Level: 2/3  What is this?
Table of contents

P0155 BUICK Possible Causes

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

How is the P0155 BUICK code repair?

Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

Tech Notes

The code means that there is a problem with the heater element circuit of the heated oxygen sensor. The Engine Control Module (ECM) monitors how long it take the sensor to warm up and start sending an adequate signal. The code means the the sensor is taking too long to warm up. Replacing the Front Heated Oxygen Sensor (H2OS) Bank 2 usually takes care of the problem.

What is the cost to diagnose the P0155 BUICK code

Labor: 1.0

The cost to diagnose the P0155 BUICK code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.
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When is the code detected?

The Powertrain Control Module (PCM) runs the heater test only on a cold start (depends on the cumulative air flow) and only once an ignition cycle. When you start the engine the PCM monitors the HO2S voltage. When the HO2S voltage goes above or below the bias range threshold, the PCM determines how much time it took. If the PCM detects that the process took too much time for the HO2S to enter into normal operating range, the P0155 code will set. The time the process takes the HO2S to reach operating temperature is based on the amount of air that flows into the engine.

Possible Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)
  • Possible higher fuel consumption
  • Possible more smoke from exhaust than usual

P0155 BUICK Meaning

The Powertrain Control Module (PCM) supplies a bias voltage (approximately 450 mV) on the Heated Oxygen Sensor (HO2S) signal high and low circuits. When you turn the ignition to the ON position, battery voltage is supplied to the HO2S heater. As the heater reaches the operating temperature, the HO2S voltage responds by changing from a bias voltage range to the normal operation. Typically, as the HO2S reaches the operating temperature, the HO2S voltage goes from a bias voltage to a voltage below 300 mV. Depending on the exhaust gas content, it is possible for the HO2S voltage to go above 450 mV.

More Information

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