AutoCodes – Chevrolet – P22A4 Chevrolet

P22A4 Chevrolet 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 Chevrolet 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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 753

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
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

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

What does this mean?

What are the Possible Causes of the DTC P22A4 Chevrolet?

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 Chevrolet?

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 Chevrolet 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 Chevrolet code?

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

Need Help with the Code?

Get the P22A4 Chevrolet code diagnosed by a professional: Find a repair shop in your area

Information for Specific Chevrolet Models

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

What does OBDII code P22A4 mean for my Chevrolet?

OBDII code P22A4 indicates a low voltage condition in the NOx sensor 2 heater control circuit, which can affect the performance of the NOx sensor responsible for reducing emissions.

What are the common symptoms of code P22A4 in my Chevrolet?

Common symptoms include the check engine light being illuminated, poor engine performance, increased emissions, and potential failure during emissions testing.

What could cause the P22A4 code to trigger?

Causes may include a faulty NOx sensor 2, damaged wiring or connectors in the heater circuit, a blown fuse, or issues with the engine control module (ECM).

How can I troubleshoot the P22A4 code?

Start by visually inspecting the wiring and connectors for damage. Use a multimeter to check the voltage in the heater circuit. If the wiring appears intact, consider testing or replacing the NOx sensor 2.

What should I do if I clear the P22A4 code, but it comes back?

If the code reappears after clearing, it is advisable to perform a thorough inspection of the NOx sensor and its associated circuits, as well as checking for other related codes that may provide additional context.

Is it safe to drive with a P22A4 code?

While it might be safe to drive short distances, continuing to operate the vehicle with this code can lead to increased emissions and potential damage to the engine or exhaust system, so repairs should be made as soon as possible.

How much does it typically cost to repair the P22A4 code?

Repair costs can vary widely depending on the underlying issue, but replacing a NOx sensor typically ranges from $150 to $400, including parts and labor.

Can I fix the P22A4 code myself?

If you have experience with automotive repairs, you may be able to troubleshoot and replace the NOx sensor or repair wiring issues yourself, but be cautious and consider consulting a professional if you're unsure.

Will replacing the NOx sensor 2 always fix the P22A4 code?

Not necessarily. While replacing a faulty NOx sensor can resolve the issue, if there are underlying problems with wiring or the ECM, those will also need to be addressed to fully resolve the P22A4 code.