AutoCodes – GMC – P22A9 2017 GMC Sierra

P22A9 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: P22A9 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 204

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 P22A9 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 P22A9 2017 GMC Sierra - NOx Sensor 2 Heater Feedback Circuit Low Voltage - AutoCodes.com — P22A9 2017 GMC Sierra Code - NOx Sensor 2 Heater Feedback Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P22A9 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 P22A9 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 P22A9 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 P22A9 2017 GMC Sierra code?

Need more information on how to fix the P22A9 2017 GMC Sierra code? Get Access to Factory Service Manuals

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 P22A9 2017 GMC Sierra Code

1. What are the common symptoms of OBDII code P22A9 in a 2017 GMC Sierra related to the NOx Sensor 2 Heater Feedback Circuit Low Voltage?

The common symptoms may include the illumination of the check engine light, reduced engine performance, and potential issues with emissions control.

2. What are the possible causes of the NOx Sensor 2 Heater Feedback Circuit Low Voltage fault code P22A9 in a 2017 GMC Sierra?

Potential causes include a faulty NOx sensor, damaged wiring or connectors in the sensor circuit, a malfunctioning heater element in the sensor, or issues with the vehicle's computer system.

3. How serious is the P22A9 OBDII code related to the NOx Sensor 2 Heater Feedback Circuit Low Voltage in a 2017 GMC Sierra?

While the vehicle may still be drivable with this code, it is important to address it promptly to prevent potential damage to the emissions control system and ensure optimal engine performance.

4. Can I continue driving my 2017 GMC Sierra with the NOx Sensor 2 Heater Feedback Circuit Low Voltage code P22A9?

It is generally recommended to avoid prolonged driving with this fault code present to prevent any further damage to the emissions control system and to maintain the vehicle's overall performance.

5. How can I diagnose the NOx Sensor 2 Heater Feedback Circuit Low Voltage fault code P22A9 in my 2017 GMC Sierra?

Diagnosis typically involves using an OBDII scanner to retrieve the specific fault code, inspecting the NOx sensor and its wiring for any visible damage, and testing the sensor's heater element and related components.

6. Is it possible to repair the NOx Sensor 2 Heater Feedback Circuit Low Voltage issue (P22A9) in a 2017 GMC Sierra without professional help?

While some DIY enthusiasts may attempt to address this issue, it is recommended to consult a qualified mechanic or dealership for an accurate diagnosis and proper repair to ensure the problem is resolved correctly.

7. How much does it cost to fix the NOx Sensor 2 Heater Feedback Circuit Low Voltage fault code P22A9 in a 2017 GMC Sierra?

The cost of repair can vary depending on the root cause of the issue, the need for parts replacement, and labor charges. It's advisable to obtain estimates from local mechanics or dealerships for an accurate cost assessment.

8. Can a faulty NOx Sensor 2 Heater Feedback Circuit Low Voltage (P22A9) code affect the vehicle's fuel efficiency?

Yes, a malfunctioning NOx sensor or related components can impact the vehicle's fuel efficiency by affecting the engine's performance and emissions control system, leading to potential decreases in fuel economy.

9. How long does it typically take to repair the NOx Sensor 2 Heater Feedback Circuit Low Voltage fault code P22A9 in a 2017 GMC Sierra?

The repair time can vary based on the specific cause of the issue, availability of parts, and the mechanic's workload. In general, it may take a few hours to a day to address this fault code effectively.

10. Can resetting the check engine light clear the NOx Sensor 2 Heater Feedback Circuit Low Voltage code P22A9 in a 2017 GMC Sierra?

Resetting the check engine light may temporarily clear the code, but if the underlying issue causing the fault code is not addressed, the code is likely to reappear. It's crucial to diagnose and repair the problem to prevent future occurrences.