AutoCodes – GMC – P22A4 GMC

P22A4 GMC Code - NOx Sensor 2 Heater Control 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: P22A4 GMC indicates NOx Sensor 2 Heater Control 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 833

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 P22A4 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 P22A4 GMC - NOx Sensor 2 Heater Control Circuit Low Voltage - AutoCodes.com — P22A4 GMC Code - NOx Sensor 2 Heater Control Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P22A4 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 P22A4 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 P22A4 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 P22A4 GMC code?

Need more information on how to fix the P22A4 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

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Information for Specific GMC Models

P22A4 2014 GMC Sierra — NOx Sensor 2 Heater Control Circuit Low Voltage
P22A4 2015 GMC Sierra — NOx Sensor 2 Heater Control Circuit Low Voltage
P22A4 2016 GMC Sierra — NOx Sensor 2 Heater Control Circuit Low Voltage
P22A4 2017 GMC Sierra — NOx Sensor 2 Heater Control Circuit Low Voltage
P22A4 2018 GMC Sierra — NOx Sensor 2 Heater Control 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 P22A4 GMC Code

1. What are common symptoms of OBDII code P22A4 GMC related to NOx Sensor 2 Heater Control Circuit Low Voltage?

- Common symptoms include a check engine light illuminated on the dashboard, reduced engine performance, and potential increase in emissions.

2. What are the possible causes of OBDII code P22A4 GMC indicating NOx Sensor 2 Heater Control Circuit Low Voltage?

- The code may be triggered due to a faulty NOx sensor, damaged wiring or connectors, a malfunctioning heater control circuit, or issues with the vehicle's engine control module.

3. How can I diagnose the OBDII code P22A4 GMC for NOx Sensor 2 Heater Control Circuit Low Voltage?

- Diagnosis typically involves using an OBDII scanner to retrieve the specific fault code, inspecting the NOx sensor and its wiring for any visible damage, and testing the heater control circuit for proper functionality.

4. Can I still drive my vehicle with OBDII code P22A4 GMC related to NOx Sensor 2 Heater Control Circuit Low Voltage?

- It is generally not recommended to drive with this code active, as it can lead to increased emissions and potential engine performance issues. It's best to address the problem promptly.

5. How can I repair OBDII code P22A4 GMC for NOx Sensor 2 Heater Control Circuit Low Voltage?

- Repair options may include replacing the faulty NOx sensor, repairing damaged wiring or connectors, fixing the heater control circuit, or reprogramming the engine control module if necessary.

6. Can a DIY enthusiast fix OBDII code P22A4 GMC indicating NOx Sensor 2 Heater Control Circuit Low Voltage?

- While some experienced DIYers may be able to address this issue, it is recommended to seek professional help, especially when dealing with sensitive emissions control components.

7. Is it necessary to reset the OBDII code P22A4 GMC after repairing the NOx Sensor 2 Heater Control Circuit Low Voltage issue?

- Yes, it is important to reset the fault code using an OBDII scanner after completing the repairs. This will clear the code from the system and allow you to monitor the vehicle's performance.

8. What are the potential long-term effects of ignoring OBDII code P22A4 GMC for NOx Sensor 2 Heater Control Circuit Low Voltage?

- Ignoring this code can lead to increased emissions, potential damage to the catalytic converter, decreased fuel efficiency, and may cause the vehicle to fail emissions tests.

9. Is OBDII code P22A4 GMC related to NOx Sensor 2 Heater Control Circuit Low Voltage a common issue in GMC vehicles?

- While it may not be as common as some other codes, issues with the NOx sensor and its heater control circuit can occur in GMC vehicles, especially in models equipped with advanced emissions control systems.

10. How can I prevent OBDII code P22A4 GMC from recurring in the future after repairing the NOx Sensor 2 Heater Control Circuit Low Voltage problem?

- Regular maintenance, including checking the NOx sensor and related components during scheduled service intervals, can help prevent this code from recurring. Maintaining clean wiring and connectors is also important.