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P115F 2018 GMC Sierra Code - O2 Reference Voltage Circuit Low Voltage (NOx Sensor 1)

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
P115F 2018 GMC Sierra indicates O2 Reference Voltage Circuit Low Voltage (NOx Sensor 1).
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 273
How popular is this code, among other codes? Low
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Table of contents Created and updated by William Orellana on Mar 24, 2024
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Code P115F 2018 GMC Sierra 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 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 P115F 2018 GMC Sierra - O2 Reference Voltage Circuit Low Voltage (NOx Sensor 1) - AutoCodes.com
P115F 2018 GMC Sierra Code - O2 Reference Voltage Circuit Low Voltage (NOx Sensor 1)
What does this mean?

What are the Possible Causes of the DTC P115F 2018 GMC Sierra?

  • 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 P115F 2018 GMC Sierra?

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 P115F 2018 GMC Sierra 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 P115F 2018 GMC Sierra code?

Need more information on how to fix the P115F 2018 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

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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 P115F 2018 GMC Sierra Code

1. What does the OBDII code P115F mean on a 2018 GMC Sierra?

P115F refers to "O2 Reference Voltage Circuit Low Voltage (NOx Sensor 1)," indicating an issue with the reference voltage signal from the NOx sensor.

2. What are the common symptoms of code P115F in a 2018 GMC Sierra?

Symptoms may include the check engine light turning on, reduced engine performance, poor fuel efficiency, and possible activation of limp mode.

3. What causes the P115F code to appear on a 2018 GMC Sierra?

Common causes include a faulty NOx sensor, damaged wiring or connectors in the circuit, a failed ECM, or corrosion in the harness connections.

4. Can I drive my 2018 GMC Sierra with a P115F code?

Driving with this code is not recommended as it can lead to reduced performance, higher emissions, and potential damage to other components.

5. How do I fix the P115F code on my 2018 GMC Sierra?

Repairs may include inspecting and repairing the NOx sensor wiring, replacing the NOx sensor, cleaning corroded connectors, or updating/reprogramming the ECM if necessary.

6. How do I diagnose the P115F code on a 2018 GMC Sierra?

Use a scan tool to confirm the code, then check the NOx sensor's wiring, connectors, and reference voltage to identify any faults or irregularities.

7. Is the NOx sensor the same as an oxygen (O2) sensor?

No, the NOx sensor measures nitrogen oxides in the exhaust, while an O2 sensor detects oxygen levels. Both are part of the emissions control system but serve different purposes.

8. How much does it cost to repair the P115F code on a GMC Sierra?

Repair costs vary; replacing a NOx sensor typically ranges from $300 to $600, while repairing wiring or connectors may be less expensive.

9. Can a bad NOx sensor cause engine performance issues in a 2018 GMC Sierra?

Yes, a malfunctioning NOx sensor can negatively affect engine performance by disrupting the emissions control system and fuel-air mixture.

10. How can I prevent the P115F code from reoccurring?

Regularly inspect the NOx sensor, wiring, and connectors for damage or corrosion, and address any exhaust or ECM issues promptly.

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