AutoCodes – GMC – P1194 2014 GMC Sierra

P1194 2014 GMC Sierra Code - O2 Low Reference Circuit High 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: P1194 2014 GMC Sierra indicates O2 Low Reference Circuit High 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.

Save to My Repairs My Repairs

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

Code Popularity 182

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 P1194 2014 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 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 P1194 2014 GMC Sierra - O2 Low Reference Circuit High Voltage (NOx Sensor 1) - AutoCodes.com — P1194 2014 GMC Sierra Code - O2 Low Reference Circuit High Voltage (NOx Sensor 1)

What does this mean?

What are the Possible Causes of the DTC P1194 2014 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 P1194 2014 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 P1194 2014 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 P1194 2014 GMC Sierra code?

Need more information on how to fix the P1194 2014 GMC Sierra code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1194 2014 GMC Sierra code diagnosed by a professional: Find a repair shop in your area

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 P1194 2014 GMC Sierra Code

1. What does the OBDII code P1194 mean on a 2014 GMC Sierra?

P1194 indicates an issue with the O2 Low Reference Circuit High Voltage for NOx Sensor 1. This means the sensor is detecting an abnormally high voltage in the low reference circuit.

2. What are the common symptoms of code P1194 in a 2014 GMC Sierra?

Symptoms can include the Check Engine Light turning on, reduced fuel efficiency, rough idling, poor engine performance, and potential difficulty passing emissions tests.

3. What causes the P1194 code in a 2014 GMC Sierra?

Common causes include a faulty NOx sensor, damaged wiring or connectors in the low reference circuit, corrosion on electrical components, or a problem with the engine control module (ECM).

4. Can I drive my 2014 GMC Sierra with the P1194 code?

While the vehicle may still be drivable, ignoring the code can lead to decreased fuel efficiency, increased emissions, and potential damage to other engine components over time.

5. How do you diagnose the P1194 code in a 2014 GMC Sierra?

A technician will typically use a scan tool to read live data, inspect the wiring and connectors for damage, check for proper ground connections, and test the NOx sensor's functionality.

6. How is the P1194 code fixed on a 2014 GMC Sierra?

Repairs may involve replacing the faulty NOx sensor, repairing or replacing damaged wiring or connectors, cleaning corroded connections, or reprogramming or replacing the ECM if necessary.

7. How much does it cost to fix the P1194 code on a 2014 GMC Sierra?

The cost depends on the specific issue but typically ranges from $200 to $600, with NOx sensor replacement being the most common expense.

8. Can a bad NOx sensor cause the P1194 code?

Yes, a faulty NOx sensor is one of the most common causes of the P1194 code as it directly monitors and reports voltage levels in the low reference circuit.

9. What happens if the P1194 code is not fixed on a 2014 GMC Sierra?

If unresolved, the P1194 code can lead to long-term engine performance issues, higher emissions, and possible damage to the exhaust system or catalytic converter.

10. Can I clear the P1194 code without repairing the issue on my 2014 GMC Sierra?

While clearing the code with a scan tool may temporarily turn off the Check Engine Light, the issue is likely to return if the underlying problem is not addressed.