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P22A8 2014 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 2014 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 139
How popular is this code, among other codes? Low
What is this?
Table of contents Created and updated by William Orellana on Mar 24, 2024
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Code P22A8 2014 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 2014 GMC Sierra - NOx Sensor 2 Heater Feedback Circuit Low Voltage - AutoCodes.com
P22A8 2014 GMC Sierra Code - NOx Sensor 2 Heater Feedback Circuit Low Voltage
What does this mean?

What are the Possible Causes of the DTC P22A8 2014 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 2014 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 2014 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 2014 GMC Sierra code?

Need more information on how to fix the P22A8 2014 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P22A8 2014 GMC Sierra code diagnosed by a professional: Find a repair shop in your area

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 2014 GMC Sierra Code

1. What does the OBDII code P22A8 mean on a 2014 GMC Sierra?

P22A8 indicates a problem with the NOx Sensor 2 Heater Feedback Circuit, specifically low voltage. This sensor monitors nitrogen oxide levels in the exhaust system.

2. What are the common symptoms of a P22A8 code?

Symptoms include a check engine light, reduced fuel efficiency, decreased engine performance, and possible issues with emissions system functionality.

3. What causes the P22A8 code to trigger?

Possible causes include a faulty NOx sensor, damaged sensor wiring or connectors, a blown fuse for the sensor heater, or a malfunctioning powertrain control module (PCM).

4. Is it safe to drive with a P22A8 code on a 2014 GMC Sierra?

While the vehicle may still be drivable, driving with this code can lead to increased emissions, reduced fuel economy, and potential damage to the emissions system over time.

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

Diagnosis involves using an OBDII scanner to confirm the code, inspecting the wiring and connectors for damage, checking the heater circuit’s fuse, and testing the NOx sensor for proper operation.

6. Can a P22A8 code affect the GMC Sierra’s emissions test?

Yes, this code can cause the vehicle to fail an emissions test due to improper NOx sensor function and increased emissions.

7. How do you fix a P22A8 code on a 2014 GMC Sierra?

Common fixes include replacing the faulty NOx sensor, repairing damaged wiring or connectors, replacing a blown fuse, or reprogramming or replacing the PCM if necessary.

8. How much does it cost to repair a P22A8 code?

The cost varies depending on the repair needed. Replacing the NOx sensor typically costs $300-$700, while wiring repairs or PCM replacement can add to the expense.

9. Can a P22A8 code be cleared without fixing the underlying issue?

The code can be cleared temporarily with an OBDII scanner, but it will likely return unless the root cause of the issue is resolved.

10. Does the P22A8 code only apply to NOx Sensor 2?

Yes, this code specifically pertains to NOx Sensor 2, which is typically located downstream in the exhaust system, after the catalytic converter.

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