AutoCodes – GMC – P22A0 GMC

P22A0 GMC Code - NOx Sensor 2 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: P22A0 GMC indicates NOx Sensor 2 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 8,616

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
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P22A0 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 P22A0 GMC - NOx Sensor 2 Circuit Low Voltage - AutoCodes.com — P22A0 GMC Code - NOx Sensor 2 Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P22A0 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 P22A0 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 does this mean?

Code Tech Notes

There is a Factory Service Bulletin for the following GMC models:
2010 GMC Savana
2011 GMC Savana
2011 GMC Sierra
GMC Factory Service Bulletin OBDII Code P22A0

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P22A0 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 P22A0 GMC code?

Need more information on how to fix the P22A0 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P22A0 GMC code diagnosed by a professional: Find a repair shop in your area

Information for Specific GMC Models

P22A0 2014 GMC Sierra — NOx Sensor 2 Circuit Low Voltage
P22A0 2015 GMC Sierra — NOx Sensor 2 Circuit Low Voltage
P22A0 2016 GMC Sierra — NOx Sensor 2 Circuit Low Voltage
P22A0 2017 GMC Sierra — NOx Sensor 2 Circuit Low Voltage
P22A0 2018 GMC Sierra — NOx Sensor 2 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 P22A0 GMC Code

1. What does the OBDII code P22A0 mean on a GMC vehicle?

P22A0 refers to a low voltage issue in the circuit of NOx Sensor 2, which monitors nitrogen oxide levels in the exhaust system.

2. What are the common symptoms of code P22A0 in GMC vehicles?

Symptoms may include a check engine light, reduced engine performance, increased emissions, and in some cases, poor fuel efficiency.

3. What causes the P22A0 code to appear in GMC vehicles?

Common causes include a faulty NOx sensor, damaged wiring or connectors, excessive soot buildup on the sensor, or issues with the engine control module (ECM).

4. Can a dirty NOx sensor trigger the P22A0 code?

Yes, excessive soot or carbon buildup on the NOx sensor can cause it to malfunction and lead to the P22A0 code.

5. How do I diagnose the P22A0 code on my GMC?

Start by inspecting the wiring and connectors for damage, testing the NOx sensor voltage output, and using a scan tool to monitor live data from the sensor.

6. Is the P22A0 code serious, and can I keep driving with it?

While the vehicle may still be drivable, ignoring the issue can lead to increased emissions, potential engine performance problems, and damage to the exhaust system.

7. How do you fix the P22A0 code on a GMC?

Repairs typically involve replacing the faulty NOx sensor, repairing damaged wiring, or updating the ECM software if necessary.

8. How much does it cost to fix the P22A0 code on a GMC?

The cost can range from $200 to $500, depending on the price of the NOx sensor and labor charges, though wiring repairs may cost less.

9. Can a faulty ECM cause the P22A0 code?

Yes, a malfunctioning ECM can misinterpret sensor data or fail to provide proper voltage, leading to the P22A0 code.

10. Do I need to clear the P22A0 code after repairs?

Yes, after completing repairs, use an OBDII scanner to clear the code and ensure it does not return during a test drive.

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