AutoCodes – Generic – P22B6

P22B6 Code - HO2S Pump Current Trim Circuit Low Voltage Sensor 2

Quick Answer

The oxygen content of the exhaust is measured via the nitrogen oxide (NOx) sensors. Common causes include Faulty Nitrogen Oxide (NOx) Sensor 2, Nitrogen Oxide Sensor 2 harness is open or shorted, Nitrogen Oxide 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: P22B6 indicates HO2S Pump Current Trim Circuit Low Voltage Sensor 2.
Common causes: Common causes include Faulty Nitrogen Oxide (NOx) Sensor 2, Nitrogen Oxide Sensor 2 harness is open or shorted, Nitrogen Oxide 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 1,459

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 Sep 30, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
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Code P22B6 Description

The oxygen content of the exhaust is measured via the nitrogen oxide (NOx) sensors. 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 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 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 when the NOx sensor module detects a fault in the NOx sensor circuitry or a performance fault in the NOx sensor.

OBDII Code P22B6 - HO2S Pump Current Trim Circuit Low Voltage Sensor 2 - AutoCodes.com — P22B6 Code - HO2S Pump Current Trim Circuit Low Voltage Sensor 2

What does this mean?

What are the Possible Causes of the DTC P22B6?

Faulty Nitrogen Oxide (NOx) Sensor 2
Nitrogen Oxide Sensor 2 harness is open or shorted
Nitrogen Oxide Sensor 2 circuit poor electrical connection

How to Fix the DTC P22B6?

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 P22B6 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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Information for Specific Makes

P22B6 Buick — HO2S Pump Current Trim Circuit Low Voltage Sensor 2
P22B6 Cadillac — HO2S Pump Current Trim Circuit Low Voltage Sensor 2
P22B6 Chevrolet — HO2S Pump Current Trim Circuit Low Voltage Sensor 2
P22B6 GMC — HO2S Pump Current Trim Circuit Low Voltage Sensor 2

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.