AutoCodes – GMC – P22A9 GMC

P22A9 GMC 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 GMC 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 315

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

What does this mean?

What are the Possible Causes of the DTC P22A9 GMC?

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 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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P22A9 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 P22A9 GMC code?

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

Need Help with the Code?

Get the P22A9 GMC code diagnosed by a professional: Find a repair shop in your area

Information for Specific GMC Models

P22A9 2014 GMC Sierra — NOx Sensor 2 Heater Feedback Circuit Low Voltage
P22A9 2015 GMC Sierra — NOx Sensor 2 Heater Feedback Circuit Low Voltage
P22A9 2016 GMC Sierra — NOx Sensor 2 Heater Feedback Circuit Low Voltage
P22A9 2017 GMC Sierra — NOx Sensor 2 Heater Feedback Circuit Low Voltage
P22A9 2018 GMC Sierra — NOx Sensor 2 Heater Feedback Circuit Low Voltage

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 GMC Code

1. What are the common symptoms of OBDII code P22A9 GMC?

- Common symptoms include decreased fuel efficiency, rough engine performance, and the illumination of the check engine light.

2. What does the OBDII code P22A9 GMC indicate?

- This code indicates a low voltage condition in the feedback circuit of the NOx Sensor 2 heater in the vehicle's exhaust system.

3. What are the possible causes of OBDII code P22A9 GMC?

- Possible causes include a faulty NOx Sensor 2 heater, damaged wiring or connectors in the sensor circuit, or a malfunctioning engine control module (ECM).

4. How can I diagnose the issue related to OBDII code P22A9 GMC?

- Diagnosing the issue involves using a scan tool to read and interpret the fault code, inspecting the NOx Sensor 2 heater circuit for wiring damage, and testing the sensor's resistance and voltage.

5. Can I continue driving my vehicle with OBDII code P22A9 GMC?

- It is not recommended to continue driving the vehicle with this code present, as it can lead to increased emissions, potential damage to the catalytic converter, and poor engine performance.

6. What are the repair options for OBDII code P22A9 GMC?

- Repair options include replacing the faulty NOx Sensor 2 heater, repairing damaged wiring or connectors, and resetting the fault code with a scan tool after completing the repairs.

7. Can I fix OBDII code P22A9 GMC myself?

- Depending on your experience and access to tools, you may be able to fix this issue yourself by following repair guides and being cautious when handling electrical components.

8. How much does it cost to repair OBDII code P22A9 GMC at a mechanic?

- The cost of repair can vary depending on the labor rates of the mechanic and the price of parts, but typically, the total cost can range from $200 to $500.

9. How long does it take to repair OBDII code P22A9 GMC?

- Repair times can vary based on the extent of the issue and the availability of parts, but a professional mechanic may take around 1-2 hours to diagnose and repair the problem.

10. Will resetting the fault code make OBDII code P22A9 GMC go away permanently?

- Resetting the fault code may temporarily turn off the check engine light, but if the underlying issue is not fixed, the code is likely to reappear after driving the vehicle for some time.