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P22A8 2017 GMC Sierra Code - NOx Sensor 2 Heater Feedback Circuit Low Voltage

Quick Answer

The Nitrogen Oxides (NOx) sensors are part of the selective catalytic reduction system, a device used to reduce NOx emission on diesel engines. Common causes include Faulty Nitrogen Oxides (NOx) Sensor 2, Nitrogen Oxides Sensor 2 harness is open or shorted, Nitrogen Oxides 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: P22A8 2017 GMC Sierra indicates NOx Sensor 2 Heater Feedback Circuit Low Voltage.
Common causes: Common causes include Faulty Nitrogen Oxides (NOx) Sensor 2, Nitrogen Oxides Sensor 2 harness is open or shorted, Nitrogen Oxides 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 160

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Mar 24, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P22A8 2017 GMC Sierra Description

The Nitrogen Oxides (NOx) sensors are part of the selective catalytic reduction system, a device used to reduce NOx emission on diesel engines. There are two NOx sensors, one placed upstream of selective catalytic reduction, to measure inlet NOx concentration, and one placed downstream. They are connected with the control module via CAN and all the information is exchanged through it. Since it is a smart sensor, all the electrical monitoring is performed inside the sensor and only the results are sent to the Engine Control Module (ECM). Each NOx sensor contains a sensing cell, a pumping cell, and a heater. A sample of exhaust gas passes through a diffusion gap between the sensing cell and the pumping cell. The NOx sensor maintains a constant reference voltage across the sensing cell. An electronic circuit within the sensor controls the pump current through the pumping cell in order to maintain a constant voltage in the sensing cell. The amount of current required to maintain the reference voltage in the sensing cell is proportional to the concentration of NOx in the exhaust. The ECM varies the amount of diesel exhaust fluid (reductant) added by varying the reductant injector duty cycle in response to changes in engine exhaust NOx levels. The smart NOx sensors consist of two components, the NOx module and the NOx sensor element that are serviced as a unit. A circuit or performance condition with a NOx sensor is detected by the NOx sensor module. The smart NOx sensor module communicates the condition to the ECM over the serial data line. The ECM sets a DTC when a serial data message is received from the NOx sensor module. The Diagnostic Trouble Code (DTC) will be set if the ECM software detects a fault in the NOx sensor circuitry or a performance fault in the NOx sensor for greater than 2 s.

OBDII Code P22A8 2017 GMC Sierra - NOx Sensor 2 Heater Feedback Circuit Low Voltage - AutoCodes.com — P22A8 2017 GMC Sierra Code - NOx Sensor 2 Heater Feedback Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P22A8 2017 GMC Sierra?

Faulty Nitrogen Oxides (NOx) Sensor 2
Nitrogen Oxides Sensor 2 harness is open or shorted
Nitrogen Oxides Sensor 2 circuit poor electrical connection

How to Fix the DTC P22A8 2017 GMC Sierra?

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 P22A8 2017 GMC Sierra 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 P22A8 2017 GMC Sierra code?

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Need Help with the Code?

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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 P22A8 2017 GMC Sierra Code

1. What does the OBDII code P22A8 mean for a 2017 GMC Sierra?

P22A8 indicates a low voltage issue in the NOx Sensor 2 Heater Feedback Circuit, which monitors the heater used to bring the NOx sensor to operating temperature.

2. What are the common symptoms of the P22A8 code on a 2017 GMC Sierra?

Symptoms may include an illuminated Check Engine Light, decreased fuel efficiency, poor engine performance, and the vehicle possibly entering limp mode.

3. What causes the P22A8 code to appear on a 2017 GMC Sierra?

Common causes include a faulty NOx sensor, a damaged or corroded wiring harness, a blown fuse, a defective NOx sensor heater, or issues with the ECM.

4. How do you diagnose the P22A8 code on a GMC Sierra?

Diagnosis typically involves scanning for trouble codes, visually inspecting the NOx sensor wiring and connector, testing the heater circuit for proper voltage, and verifying sensor functionality.

5. Can I drive my 2017 GMC Sierra with a P22A8 code?

Driving with this code is not recommended as it can lead to reduced performance, higher emissions, and potential damage to the catalytic converter over time.

6. How is the P22A8 code fixed on a 2017 GMC Sierra?

Repairs may include replacing the NOx sensor, repairing or replacing damaged wiring, replacing a blown fuse, or reprogramming/updating the ECM if necessary.

7. How much does it cost to fix the P22A8 code on a GMC Sierra?

Repair costs vary but typically range from $300 to $800, depending on whether the NOx sensor needs replacement or if wiring repairs are required.

8. Can a faulty NOx sensor cause other issues in a 2017 GMC Sierra?

Yes, a faulty NOx sensor can lead to poor fuel economy, increased emissions, and potential damage to the exhaust aftertreatment system.

9. What tools are needed to diagnose the P22A8 code?

Tools include an OBDII scanner, a multimeter for testing voltage, and potentially a wiring diagram to trace the circuit.

10. Is the P22A8 code covered under warranty for a 2017 GMC Sierra?

It may be covered under the emissions warranty, which typically lasts longer than the standard powertrain warranty. Check with your dealer for details.