AutoCodes – GMC – P22A9 2016 GMC Sierra

P22A9 2016 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 2016 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 215

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 2016 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 2016 GMC Sierra - NOx Sensor 2 Heater Feedback Circuit Low Voltage - AutoCodes.com — P22A9 2016 GMC Sierra Code - NOx Sensor 2 Heater Feedback Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P22A9 2016 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 2016 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 2016 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 2016 GMC Sierra code?

Need more information on how to fix the P22A9 2016 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 2016 GMC Sierra Code

1. What does the OBDII code P22A9 mean on a 2016 GMC Sierra?

P22A9 indicates a problem with the NOx Sensor 2 Heater Feedback Circuit, specifically low voltage, which affects the proper functioning of the sensor.

2. What are the symptoms of a P22A9 code?

Symptoms may include an illuminated check engine light, reduced fuel efficiency, poor engine performance, and potential issues with emissions compliance.

3. What causes the P22A9 code to appear?

Common causes include a faulty NOx sensor, damaged wiring or connectors in the sensor circuit, or a malfunctioning NOx sensor heater.

4. How does the NOx Sensor Heater affect vehicle performance?

The heater helps the NOx sensor reach its operating temperature more quickly, ensuring accurate emissions readings. If it fails, the sensor may provide incorrect information.

5. Can I drive my 2016 GMC Sierra with a P22A9 code?

While the truck may still operate, driving with this code can lead to increased emissions, reduced fuel efficiency, and potential damage to the exhaust system.

6. How do I diagnose a P22A9 code?

Start by inspecting the NOx sensor wiring and connectors for damage or corrosion. Use a multimeter to check for proper voltage and resistance in the circuit.

7. How do I fix the P22A9 code on a 2016 GMC Sierra?

Repairs may include replacing the NOx sensor, repairing damaged wiring, or updating the vehicleâ€™s software if a known issue exists.

8. How much does it cost to fix a P22A9 code?

The cost can range from $200 to $600 or more, depending on whether you need to replace the NOx sensor or perform additional repairs.

9. Can a bad NOx sensor damage the engine?

A faulty NOx sensor wonâ€™t directly damage the engine but can lead to poor performance, increased emissions, and potential damage to the catalytic converter over time.

10. Is the P22A9 code covered under warranty for a 2016 GMC Sierra?

This depends on your vehicle's warranty coverage. Emissions-related components may be covered under the federal emissions warranty, so check with your dealership.