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P11D8 Cadillac 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 Cadillac 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 571

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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

What does this mean?

What are the Possible Causes of the DTC P11D8 Cadillac?

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 Cadillac?

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 Cadillac 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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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 Cadillac Code

1. What are the common symptoms of OBDII code P11D8 in a Cadillac related to the O2 Pump Current Control Circuit (NOx Sensor 2)?

- Common symptoms may include reduced engine performance, increased fuel consumption, rough idling, and the illumination of the Check Engine light.

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

- Potential causes of this code include a faulty O2 pump, damaged wiring or connectors in the current control circuit, issues with the NOx sensor 2, or a malfunctioning powertrain control module (PCM).

3. How can I diagnose the O2 Pump Current Control Circuit issue for OBDII code P11D8 in my Cadillac?

- Diagnosis typically involves using a diagnostic scan tool to retrieve the specific trouble code, checking the wiring and connectors for any visible damage, and testing the O2 pump and NOx sensor 2 for proper functioning.

4. Can I drive my Cadillac with OBDII code P11D8 present?

- It is not recommended to drive your vehicle with this code present, as it can lead to decreased fuel efficiency and potential damage to other components if left unresolved.

5. What are some repair tips for fixing OBDII code P11D8 in a Cadillac?

- Repair tips may include checking and repairing any damaged wiring or connectors, replacing the O2 pump if faulty, inspecting and replacing the NOx sensor 2 if necessary, and resetting the trouble code with a diagnostic tool after repairs are completed.

6. Is it possible to clear OBDII code P11D8 in a Cadillac by simply resetting the Check Engine light?

- Resetting the Check Engine light may temporarily clear the code, but it is important to address the underlying issue causing the fault code to prevent it from reoccurring in the future.

7. How much does it typically cost to repair OBDII code P11D8 related to the O2 Pump Current Control Circuit in a Cadillac?

- Repair costs can vary depending on the specific cause of the issue, but they may range from $200 to $600 or more, including parts and labor.

8. Can OBDII code P11D8 in a Cadillac be triggered by a loose gas cap?

- While a loose gas cap can trigger some OBDII codes related to the fuel system, code P11D8 specifically relates to issues with the O2 pump current control circuit and NOx sensor 2, so a loose gas cap is unlikely to be the cause in this case.