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AutoCodes – GMC – P2209 GMC

P2209 GMC Code - NOx Sensor 1 Heater Control Circuit

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, Nitrogen Oxides Sensor harness is open or shorted, Nitrogen Oxides Sensor 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
P2209 GMC indicates NOx Sensor 1 Heater Control Circuit.
Common causes
Common causes include Faulty Nitrogen Oxides (NOx) Sensor, Nitrogen Oxides Sensor harness is open or shorted, Nitrogen Oxides Sensor 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 2,391
How popular is this code, among other codes? Low
What is this?
Table of contents Created and updated by William Orellana on Mar 29, 2024
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Code P2209 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 P2209 GMC - NOx Sensor 1 Heater Control Circuit - AutoCodes.com
P2209 GMC Code - NOx Sensor 1 Heater Control Circuit
What does this mean?

What are the Possible Causes of the DTC P2209 GMC?

  • Faulty Nitrogen Oxides (NOx) Sensor
  • Nitrogen Oxides Sensor harness is open or shorted
  • Nitrogen Oxides Sensor circuit poor electrical connection

How to Fix the DTC P2209 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 P2209 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 P2209 GMC code?

Need more information on how to fix the P2209 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P2209 GMC code diagnosed by a professional: Find a repair shop in your area

Information for Specific GMC Models

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 P2209 GMC Code

1. What does the OBDII code P2209 mean for a GMC vehicle?

P2209 indicates an issue with the NOx Sensor 1 Heater Control Circuit, which is responsible for heating the sensor to accurately measure nitrogen oxide levels in the exhaust.

2. What are the common symptoms of code P2209 in a GMC?

Symptoms may include a check engine light, reduced fuel efficiency, poor engine performance, and possible issues with emissions testing.

3. What causes the P2209 code to be triggered in a GMC vehicle?

Common causes include a malfunctioning NOx sensor heater, damaged wiring or connectors, a failed NOx sensor, or issues with the engine control module (ECM).

4. Can I drive my GMC with the P2209 code active?

While the vehicle may still be drivable, prolonged operation with this code could lead to increased emissions and potential damage to the catalytic converter.

5. How is the P2209 code diagnosed in a GMC?

Technicians use a diagnostic scan tool, inspect the NOx sensor and heater circuit wiring, and test the functionality of the sensor and its heater control system.

6. How do you fix the P2209 code on a GMC vehicle?

Repairs may include replacing the NOx Sensor 1, repairing or replacing damaged wiring, cleaning connectors, or updating/reprogramming the ECM.

7. How much does it cost to repair the P2209 code on a GMC?

Repair costs can vary but typically range from $200 to $700, depending on whether the NOx sensor needs replacement or if wiring repairs are required.

8. Can a faulty NOx sensor cause long-term damage to a GMC engine?

Yes, a malfunctioning NOx sensor can lead to improper engine performance and potentially damage the catalytic converter over time.

9. Is the P2209 code related to emissions testing?

Yes, a malfunctioning NOx sensor can cause your GMC to fail emissions testing due to inaccurate readings of nitrogen oxide levels.

10. What tools are needed to troubleshoot the P2209 code on a GMC?

You’ll need a diagnostic scan tool, a multimeter to test the circuit, and potentially wiring repair tools or replacement parts.

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