AutoCodes – Chevrolet – P1194 Chevrolet

P1194 Chevrolet 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 Chevrolet 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.

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Code Popularity 839

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 29, 2024

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1194 Chevrolet 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 Chevrolet - O2 Low Reference Circuit High Voltage (NOx Sensor 1) - AutoCodes.com — P1194 Chevrolet Code - O2 Low Reference Circuit High Voltage (NOx Sensor 1)

What does this mean?

What are the Possible Causes of the DTC P1194 Chevrolet?

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 Chevrolet?

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 Chevrolet 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 Chevrolet code?

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

Need Help with the Code?

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Information for Specific Chevrolet Models

P1194 2014 Chevrolet Silverado — O2 Low Reference Circuit High Voltage (NOx Sensor 1)
P1194 2015 Chevrolet Silverado — O2 Low Reference Circuit High Voltage (NOx Sensor 1)
P1194 2016 Chevrolet Silverado — O2 Low Reference Circuit High Voltage (NOx Sensor 1)
P1194 2017 Chevrolet Silverado — O2 Low Reference Circuit High Voltage (NOx Sensor 1)
P1194 2018 Chevrolet Silverado — O2 Low Reference Circuit High Voltage (NOx Sensor 1)

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 Chevrolet Code

1. What are the common symptoms of OBDII code P1194 in a Chevrolet related to the O2 Low Reference Circuit High Voltage (NOx Sensor 1)?

- Common symptoms may include poor engine performance, decreased fuel efficiency, and the illumination of the Check Engine light.

2. What are the possible causes of OBDII code P1194 in a Chevrolet indicating an issue with the O2 Low Reference Circuit High Voltage (NOx Sensor 1)?

- Possible causes include a faulty NOx sensor, damaged wiring or connectors in the circuit, or issues with the engine control module (ECM).

3. How can I diagnose OBDII code P1194 in my Chevrolet to determine the exact cause of the O2 Low Reference Circuit High Voltage (NOx Sensor 1) problem?

- Diagnosis typically involves using an OBDII scanner to retrieve the trouble codes, performing a visual inspection of the sensor and circuit, and testing the sensor's voltage and resistance.

4. What are some repair tips for fixing OBDII code P1194 in a Chevrolet related to the O2 Low Reference Circuit High Voltage (NOx Sensor 1)?

- Repair tips may include checking and repairing any damaged wiring or connectors, replacing the NOx sensor if faulty, and resetting the ECM after repairs are completed.

5. Can I continue driving my Chevrolet with OBDII code P1194 indicating an issue with the O2 Low Reference Circuit High Voltage (NOx Sensor 1)?

- It is recommended not to ignore the issue and to have the problem diagnosed and repaired promptly to prevent potential damage to the vehicle's engine and emissions system.

6. Is it possible to reset the Check Engine light after fixing OBDII code P1194 in a Chevrolet?

- Yes, the Check Engine light can typically be reset using an OBDII scanner after the issue causing the O2 Low Reference Circuit High Voltage (NOx Sensor 1) problem has been addressed.

7. How much does it typically cost to repair OBDII code P1194 in a Chevrolet related to the O2 Low Reference Circuit High Voltage (NOx Sensor 1)?

- The cost of repair can vary depending on the exact cause of the issue, but it may involve expenses for parts and labor, with the sensor replacement being a common repair step.

8. Are there any preventative maintenance steps I can take to avoid encountering OBDII code P1194 in my Chevrolet?

- Regular vehicle maintenance, such as checking and replacing sensors as recommended by the manufacturer, can help prevent issues like O2 Low Reference Circuit High Voltage (NOx Sensor 1) problems.

9. Is it safe to attempt DIY repairs for OBDII code P1194 in a Chevrolet, or should I seek professional help?

- While some simple tasks like checking connectors can be done DIY, diagnosing and repairing complex issues related to the NOx sensor circuit may be best left to automotive professionals for accurate and thorough resolution.