AutoCodes – Generic – P11D8

P11D8 Code - O2 Pump Current Control Circuit (NOx Sensor 2)

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 2, Nitrogen Oxides Sensor 2 harness is open or shorted, Nitrogen Oxides Sensor 2 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: P11D8 indicates O2 Pump Current Control Circuit (NOx Sensor 2).
Common causes: Common causes include Faulty Nitrogen Oxides (NOx) Sensor 2, Nitrogen Oxides Sensor 2 harness is open or shorted, Nitrogen Oxides Sensor 2 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 3,169

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
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Code P11D8 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 P11D8 - O2 Pump Current Control Circuit (NOx Sensor 2) - AutoCodes.com — P11D8 Code - O2 Pump Current Control Circuit (NOx Sensor 2)

What does this mean?

What are the Possible Causes of the DTC P11D8?

Faulty Nitrogen Oxides (NOx) Sensor 2
Nitrogen Oxides Sensor 2 harness is open or shorted
Nitrogen Oxides Sensor 2 circuit poor electrical connection

How to Fix the DTC P11D8?

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 P11D8 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

P11D8 Buick — O2 Pump Current Control Circuit (NOx Sensor 2)
P11D8 Cadillac — O2 Pump Current Control Circuit (NOx Sensor 2)
P11D8 Chevrolet — O2 Pump Current Control Circuit (NOx Sensor 2)
P11D8 GMC — O2 Pump Current Control Circuit (NOx Sensor 2)

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 P11D8 Code

1. What are the common symptoms of OBDII code P11D8 (O2 Pump Current Control Circuit - NOx Sensor 2)?

- Common symptoms include poor engine performance, rough idling, reduced fuel efficiency, and the illumination of the Check Engine light.

2. What are the possible causes of OBDII code P11D8?

- The code P11D8 can be triggered by a faulty O2 pump, damaged wiring or connectors in the current control circuit, or a malfunctioning NOx sensor 2.

3. How can I diagnose OBDII code P11D8?

- Diagnosing this code typically involves using a diagnostic scanner to retrieve the trouble codes, checking the wiring and connectors for damage, and testing the O2 pump current control circuit and NOx sensor 2 for proper functionality.

4. What are some repair tips for resolving OBDII code P11D8?

- Repair tips may include checking and repairing any damaged wiring or connectors, replacing a faulty O2 pump, and ensuring proper connection and functioning of the NOx sensor 2.

5. Can I drive my vehicle with OBDII code P11D8?

- It is not recommended to drive the vehicle with an unresolved P11D8 code, as it can lead to further damage to the engine and emissions system. It is advisable to address the issue promptly.

6. How much does it typically cost to repair OBDII code P11D8?

- The cost of repairing OBDII code P11D8 can vary depending on the specific cause of the issue, but it may range from $200 to $600, including parts and labor.

7. Will OBDII code P11D8 cause my vehicle to fail an emissions test?

- Yes, OBDII code P11D8 can cause your vehicle to fail an emissions test, as it indicates a problem with the O2 pump current control circuit, which affects emissions control.

8. Are there any DIY fixes for OBDII code P11D8?

- DIY fixes for OBDII code P11D8 may include checking and cleaning connectors, ensuring proper wiring connections, and replacing the O2 pump or NOx sensor 2 if necessary, depending on your skill level.

9. How long does it take to repair OBDII code P11D8?

- The repair time for OBDII code P11D8 can vary depending on the extent of the issue and the availability of parts, but it may take a few hours to a full day for a professional mechanic to address the problem.

10. Can OBDII code P11D8 be intermittent?

- Yes, OBDII code P11D8 can sometimes be intermittent, especially if the issue is related to loose wiring or connectors. It is essential to address the problem promptly to prevent further complications.