AutoCodes – Generic – P116A

P116A Code - O2 Signal Circuit (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: P116A indicates O2 Signal Circuit (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 621

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 P116A 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 P116A - O2 Signal Circuit (NOx Sensor 1) - AutoCodes.com — P116A Code - O2 Signal Circuit (NOx Sensor 1)

What does this mean?

What are the Possible Causes of the DTC P116A?

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 P116A?

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 P116A 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.

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Information for Specific Makes

P116A Buick — O2 Signal Circuit (NOx Sensor 1)
P116A Cadillac — O2 Signal Circuit (NOx Sensor 1)
P116A Chevrolet — O2 Signal Circuit (NOx Sensor 1)
P116A GMC — O2 Signal Circuit (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 P116A Code

1. What are the common symptoms of OBDII code P116A (O2 Signal Circuit - NOx Sensor 1)?

The common symptoms of code P116A include poor engine performance, decreased fuel efficiency, and illuminated check engine light.

2. What does the OBDII code P116A (O2 Signal Circuit - NOx Sensor 1) indicate?

This code indicates an issue with the oxygen sensor signal circuit for the NOx Sensor 1 in the vehicle's exhaust system.

3. What are the potential causes of OBDII code P116A (O2 Signal Circuit - NOx Sensor 1)?

Potential causes of this code include a faulty NOx sensor, damaged wiring or connectors in the sensor circuit, exhaust leaks, or issues with the engine control module (ECM).

4. How can I diagnose the O2 signal circuit issue related to code P116A?

Diagnosing the O2 signal circuit issue involves checking the wiring and connectors for damage, testing the NOx sensor for proper operation, and scanning the ECM for any related fault codes.

5. Can I drive my vehicle with OBDII code P116A (O2 Signal Circuit - NOx Sensor 1)?

It is not recommended to drive your vehicle with this code present, as it can lead to further damage and poor engine performance. It's best to address the issue promptly.

6. How can I repair OBDII code P116A (O2 Signal Circuit - NOx Sensor 1) myself?

Depending on the underlying cause, you may be able to repair this code yourself by replacing the faulty NOx sensor, repairing damaged wiring or connectors, or resetting the ECM after fixing any issues.

7. Is resetting the ECM necessary after repairing OBDII code P116A (O2 Signal Circuit - NOx Sensor 1)?

Yes, resetting the ECM is recommended after repairing the issue related to this code to clear the error code and ensure proper functioning of the vehicle's emissions system.

8. Can a faulty NOx sensor cause OBDII code P116A (O2 Signal Circuit - NOx Sensor 1)?

Yes, a faulty NOx sensor is a common cause of this code. If the sensor is not functioning correctly, it can trigger the O2 signal circuit fault.

9. How much does it typically cost to repair OBDII code P116A (O2 Signal Circuit - NOx Sensor 1) at a repair shop?

The cost of repairing this code at a repair shop can vary depending on the exact cause of the issue, but it may range from $200 to $500, including parts and labor.

10. How often should the NOx sensor be replaced to prevent OBDII code P116A (O2 Signal Circuit - NOx Sensor 1)?

The NOx sensor does not have a specific replacement interval, but it is recommended to follow the manufacturer's maintenance schedule and replace the sensor if it fails or shows signs of malfunction to prevent issues like code P116A.