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P22A8 2015 Chevrolet Silverado 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 2015 Chevrolet Silverado 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 255
How popular is this code, among other codes? Low
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Table of contents Created and updated by William Orellana on Mar 24, 2024
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Code P22A8 2015 Chevrolet Silverado 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 2015 Chevrolet Silverado - NOx Sensor 2 Heater Feedback Circuit Low Voltage - AutoCodes.com
P22A8 2015 Chevrolet Silverado Code - NOx Sensor 2 Heater Feedback Circuit Low Voltage
What does this mean?

What are the Possible Causes of the DTC P22A8 2015 Chevrolet Silverado?

  • 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 2015 Chevrolet Silverado?

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 2015 Chevrolet Silverado 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 2015 Chevrolet Silverado code?

Need more information on how to fix the P22A8 2015 Chevrolet Silverado 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 P22A8 2015 Chevrolet Silverado Code

1. What does the OBDII code P22A8 mean on a 2015 Chevrolet Silverado?

P22A8 indicates a problem with the NOx Sensor 2 Heater Feedback Circuit, specifically low voltage, which affects the heater function of the downstream NOx sensor.

2. What are the symptoms of a P22A8 code on a 2015 Chevrolet Silverado?

Common symptoms include an illuminated check engine light, reduced fuel efficiency, engine performance issues, or the vehicle entering limp mode.

3. What causes the P22A8 code to appear on a 2015 Chevrolet Silverado?

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

4. Can I drive my 2015 Chevrolet Silverado with the P22A8 code?

While the vehicle may still be drivable, it is not recommended as it can lead to increased emissions, reduced performance, and potential damage to other components.

5. How do I fix the P22A8 code on my 2015 Chevrolet Silverado?

Repairs may involve inspecting and repairing damaged wiring or connectors, replacing the NOx sensor, or addressing issues with the ECM if necessary.

6. How do I diagnose the P22A8 code on my 2015 Chevrolet Silverado?

Use an OBDII scanner to confirm the code, then visually inspect the NOx sensor wiring and connectors for damage. Test the sensor's heater circuit for continuity and check for proper voltage.

7. How much does it cost to fix the P22A8 code on a 2015 Chevrolet Silverado?

The cost can vary, but replacing the NOx sensor typically ranges from $300 to $700, including parts and labor. Wiring repairs may cost less if the sensor itself is not faulty.

8. Where is NOx Sensor 2 located on a 2015 Chevrolet Silverado?

NOx Sensor 2 is located downstream in the exhaust system, typically after the diesel particulate filter (DPF).

9. Can a faulty NOx Sensor 2 cause other problems in my Silverado?

Yes, a faulty NOx sensor can lead to higher emissions, trigger additional fault codes, and potentially cause issues with the exhaust aftertreatment system.

10. Will clearing the P22A8 code fix the problem on my 2015 Chevrolet Silverado?

Clearing the code will turn off the check engine light temporarily, but if the underlying issue isn’t resolved, the code will likely reappear.

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