AutoCodes – GMC – P0056 GMC

P0056 GMC Code - HO2S Heater Control Circuit Bank 2 Sensor 2

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 2, Heated Oxygen Sensor Bank 2 Sensor 2 harness is open shorted, Heated Oxygen Sensor Bank 2 Sensor 2 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: P0056 GMC indicates HO2S Heater Control Circuit Bank 2 Sensor 2.
Common causes: Common causes include Faulty Heated Oxygen Sensor (H2OS) Bank 2 Sensor 2, Heated Oxygen Sensor Bank 2 Sensor 2 harness is open shorted, Heated Oxygen Sensor Bank 2 Sensor 2 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 5,798

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 23, 2024

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0056 GMC 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 an open circuit in the heater output low side driver circuit of the heated oxygen sensor when the heater is commanded OFF for greater than 5 s.

OBDII Code P0056 GMC - HO2S Heater Control Circuit Bank 2 Sensor 2 - AutoCodes.com — P0056 GMC Code - HO2S Heater Control Circuit Bank 2 Sensor 2

What does this mean?

What are the Possible Causes of the DTC P0056 GMC?

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

How to Fix the DTC P0056 GMC?

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 P0056 GMC 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 P0056 GMC code?

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Information for Specific GMC Models

P0056 2014 GMC Sierra — HO2S Heater Control Circuit Bank 2 Sensor 2
P0056 2015 GMC Sierra — HO2S Heater Control Circuit Bank 2 Sensor 2
P0056 2016 GMC Sierra — HO2S Heater Control Circuit Bank 2 Sensor 2
P0056 2017 GMC Sierra — HO2S Heater Control Circuit Bank 2 Sensor 2
P0056 2018 GMC Sierra — HO2S Heater Control Circuit Bank 2 Sensor 2

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 P0056 GMC Code

1. What is the meaning of OBDII code P0056 GMC?

- OBDII code P0056 GMC refers to a fault in the HO2S Heater Control Circuit for Bank 2 Sensor 2, indicating a problem with the oxygen sensor's heater element in the second sensor on the second bank of cylinders.

2. What are the common symptoms of P0056 GMC code?

- Common symptoms of P0056 GMC code include poor fuel economy, rough idling, stalling, reduced engine performance, and an illuminated Check Engine Light.

3. What are the potential causes of the P0056 GMC trouble code?

- Potential causes of the P0056 GMC trouble code include a faulty oxygen sensor, damaged wiring or connectors, a blown fuse, a malfunctioning PCM (Powertrain Control Module), or an issue with the sensor's heater circuit.

4. How can I diagnose the P0056 GMC code?

- Diagnosing the P0056 GMC code involves using an OBDII scanner to retrieve the code, inspecting the oxygen sensor and its wiring for damage, testing the sensor's heater circuit, and checking the fuse related to the sensor.

5. Can I drive my vehicle with the P0056 GMC trouble code?

- It is not recommended to drive your vehicle with the P0056 GMC trouble code present, as it can lead to engine performance issues and potential damage if left unresolved.

6. Is it possible to repair the P0056 GMC code myself?

- While some DIY enthusiasts may be able to address the P0056 GMC code by replacing the oxygen sensor or fixing wiring issues, it is recommended to seek professional help for an accurate diagnosis and proper repair.

7. How much does it typically cost to fix the P0056 GMC trouble code?

- The cost of fixing the P0056 GMC trouble code can vary depending on the underlying issue, but it may range from $100 to $300 for parts and labor if only the oxygen sensor needs replacement.

8. What are the long-term effects of ignoring the P0056 GMC trouble code?

- Ignoring the P0056 GMC trouble code can lead to decreased fuel efficiency, increased emissions, potential damage to the catalytic converter, and further engine performance issues over time.

9. Can resetting the Check Engine Light clear the P0056 GMC trouble code?

- Resetting the Check Engine Light may temporarily clear the P0056 GMC trouble code, but if the underlying issue causing the code is not addressed, the light is likely to come back on after some driving cycles.

10. How can I prevent the P0056 GMC trouble code from reoccurring?

- To prevent the P0056 GMC trouble code from reoccurring, ensure regular maintenance of your vehicle, promptly address any engine performance issues, and follow the manufacturer's recommended service schedule for the oxygen sensors.