AutoCodes – Buick – P22A8 Buick

P22A8 Buick 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 Buick 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 290

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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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 P22A8 Buick 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 Buick - NOx Sensor 2 Heater Feedback Circuit Low Voltage - AutoCodes.com — P22A8 Buick Code - NOx Sensor 2 Heater Feedback Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P22A8 Buick?

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 Buick?

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 Buick 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.

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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 Buick Code

1. What does the OBDII code P22A8 mean on a Buick?

P22A8 indicates a problem with the NOx Sensor 2 Heater Feedback Circuit, specifically low voltage, which affects the vehicle's ability to monitor and manage nitrogen oxide emissions.

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

Symptoms include an illuminated check engine light, reduced fuel efficiency, potential limp mode activation, and increased emissions.

3. What causes the P22A8 code in a Buick?

Common causes include a faulty NOx sensor heater, damaged wiring or connectors in the sensor circuit, or a failed engine control module (ECM).

4. Can I drive my Buick with the P22A8 code?

Driving with this code is not recommended as it may lead to increased emissions, reduced performance, and potential damage to the catalytic converter over time.

5. How is the P22A8 code diagnosed?

A mechanic will use a scan tool to confirm the code, inspect the NOx sensor and its wiring for damage or corrosion, and test the circuit for proper voltage and continuity.

6. How do I fix the P22A8 code on my Buick?

Repairs may involve replacing the NOx sensor 2, repairing or replacing damaged wiring or connectors, or reprogramming the ECM if necessary.

7. How much does it cost to repair the P22A8 code in a Buick?

The repair cost can range from $300 to $800 or more, depending on whether the NOx sensor or other components need to be replaced.

8. Can a dirty NOx sensor cause the P22A8 code?

While a dirty NOx sensor might not directly cause this code, it can contribute to sensor malfunction. However, low voltage in the heater feedback circuit is typically due to electrical issues.

9. How can I prevent the P22A8 code from occurring?

Regular maintenance, including inspecting and cleaning the NOx sensor and ensuring wiring and connectors are in good condition, can help prevent this issue.

10. Is the P22A8 code covered under warranty for my Buick?

Coverage depends on your vehicle's warranty terms. Emissions-related components like the NOx sensor may be covered under federal emissions warranties. Check with your dealership for details.