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AutoCodes – Chevrolet – P1194 2018 Chevrolet Silverado

P1194 2018 Chevrolet Silverado 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 2018 Chevrolet Silverado 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 260
How popular is this code, among other codes? Low
What is this?
Table of contents Created and updated by William Orellana on Mar 24, 2024
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Code P1194 2018 Chevrolet Silverado 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 2018 Chevrolet Silverado - O2 Low Reference Circuit High Voltage (NOx Sensor 1) - AutoCodes.com
P1194 2018 Chevrolet Silverado Code - O2 Low Reference Circuit High Voltage (NOx Sensor 1)
What does this mean?

What are the Possible Causes of the DTC P1194 2018 Chevrolet Silverado?

  • 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 2018 Chevrolet Silverado?

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 2018 Chevrolet Silverado 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 2018 Chevrolet Silverado code?

Need more information on how to fix the P1194 2018 Chevrolet Silverado 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 P1194 2018 Chevrolet Silverado Code

1. What does the OBDII code P1194 mean on a 2018 Chevrolet Silverado?

P1194 indicates an issue with the O2 low reference circuit high voltage, specifically related to NOx Sensor 1.

2. What are the common symptoms of a P1194 code in a 2018 Chevrolet Silverado?

Symptoms may include reduced engine performance, poor fuel economy, the check engine light turning on, and possible difficulty passing emissions tests.

3. What causes the P1194 code on a 2018 Chevrolet Silverado?

Common causes include a faulty NOx sensor, damaged wiring or connectors in the O2 reference circuit, or a malfunctioning engine control module (ECM).

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

Yes, a faulty NOx sensor is a primary cause of the P1194 code as it fails to provide accurate data to the ECM.

5. How do you fix the P1194 code on a 2018 Chevrolet Silverado?

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

6. Is it safe to drive a 2018 Chevrolet Silverado with the P1194 code?

Driving with this code is not recommended as it can lead to reduced engine efficiency, increased emissions, and potential long-term damage.

7. How is the P1194 code diagnosed on a 2018 Chevrolet Silverado?

A technician will use a scan tool to confirm the code, inspect the NOx sensor and its wiring, and measure circuit voltages to pinpoint the issue.

8. How much does it cost to repair the P1194 code on a 2018 Chevrolet Silverado?

Costs vary but typically range from $200 to $600, depending on whether the NOx sensor, wiring, or ECM needs repair or replacement.

9. Can a software update fix the P1194 code on a 2018 Chevrolet Silverado?

In some cases, a software update for the ECM may resolve the issue if it's related to incorrect sensor calibration or programming.

10. What is the role of NOx Sensor 1 in a 2018 Chevrolet Silverado?

NOx Sensor 1 monitors nitrogen oxide levels in the exhaust to help the ECM optimize emissions control and engine performance.

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