AutoCodes – GMC – P22A8 GMC

P22A8 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: P22A8 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 525

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 24, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P22A8 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 P22A8 GMC - NOx Sensor 2 Heater Feedback Circuit Low Voltage - AutoCodes.com — P22A8 GMC Code - NOx Sensor 2 Heater Feedback Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P22A8 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 P22A8 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 P22A8 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 P22A8 GMC code?

Need more information on how to fix the P22A8 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P22A8 GMC code diagnosed by a professional: Find a repair shop in your area

Information for Specific GMC Models

P22A8 2014 GMC Sierra — NOx Sensor 2 Heater Feedback Circuit Low Voltage
P22A8 2015 GMC Sierra — NOx Sensor 2 Heater Feedback Circuit Low Voltage
P22A8 2016 GMC Sierra — NOx Sensor 2 Heater Feedback Circuit Low Voltage
P22A8 2017 GMC Sierra — NOx Sensor 2 Heater Feedback Circuit Low Voltage
P22A8 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 P22A8 GMC Code

1. What are common symptoms of OBDII code P22A8 GMC related to the NOx Sensor 2 Heater Feedback Circuit Low Voltage?

The common symptoms include poor engine performance, reduced fuel efficiency, and the illumination of the check engine light.

2. What are the possible causes of OBDII code P22A8 GMC indicating an issue with the NOx Sensor 2 Heater Feedback Circuit Low Voltage?

Possible causes include a faulty NOx sensor, damaged wiring or connectors, a blown fuse, or a malfunctioning engine control module (ECM).

3. How can I diagnose the NOx Sensor 2 Heater Feedback Circuit Low Voltage issue associated with code P22A8 GMC?

Diagnosis typically involves using an OBDII scanner to retrieve the error code, inspecting the sensor wiring and connections, testing the sensor's resistance, and checking the ECM for proper functionality.

4. Can I continue driving my vehicle with OBDII code P22A8 GMC triggered by the NOx Sensor 2 Heater Feedback Circuit Low Voltage issue?

It is not recommended to drive the vehicle with this code active, as it can lead to increased emissions, potential damage to the catalytic converter, and further engine problems.

5. How can I repair OBDII code P22A8 GMC related to the NOx Sensor 2 Heater Feedback Circuit Low Voltage?

Repair options may include replacing the NOx sensor, repairing or replacing damaged wiring, ensuring proper connector connections, checking and replacing fuses if necessary, and resetting the ECM.

6. Will resetting the check engine light resolve the OBDII code P22A8 GMC issue with the NOx Sensor 2 Heater Feedback Circuit Low Voltage?

Simply resetting the check engine light will not fix the underlying problem causing the code. It is important to diagnose and address the root cause before resetting the light.

7. Are there any DIY tips for troubleshooting OBDII code P22A8 GMC linked to the NOx Sensor 2 Heater Feedback Circuit Low Voltage?

DIY troubleshooting tips include checking for visible wiring damage, ensuring connectors are securely plugged in, and inspecting the NOx sensor for any physical defects before seeking professional assistance.

8. How critical is it to address OBDII code P22A8 GMC indicating a problem with the NOx Sensor 2 Heater Feedback Circuit Low Voltage promptly?

It is important to address this code promptly to prevent potential damage to other components, ensure optimal engine performance, and maintain compliance with emissions regulations.

9. Can extreme weather conditions affect the NOx Sensor 2 Heater Feedback Circuit and trigger OBDII code P22A8 GMC in GMC vehicles?

Extreme weather conditions, particularly cold temperatures, can impact the NOx sensor's performance and potentially lead to the triggering of code P22A8 due to issues with the heater feedback circuit.

10. Is it recommended to seek professional help for resolving OBDII code P22A8 GMC associated with the NOx Sensor 2 Heater Feedback Circuit Low Voltage?

Due to the complexities involved in diagnosing and repairing issues related to NOx sensors and heater circuits, it is advisable to seek professional help from a qualified mechanic or technician to address OBDII code P22A8 effectively.