AutoCodes – GMC – P1040 GMC

P1040 GMC Code - Reductant Pump Control Circuit Shorted

Quick Answer

The selective catalytic reduction system reduces Oxides of Nitrogen (NOx) emissions by injecting a metered amount of reductant into the exhaust gas stream entering the selective catalytic reduction catalyst. Common causes include Faulty Reductant Pump and Sensor Assembly, Reductant Pump and Sensor Assembly harness is open or shorted, Reductant Pump and Sensor Assembly 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: P1040 GMC indicates Reductant Pump Control Circuit Shorted.
Common causes: Common causes include Faulty Reductant Pump and Sensor Assembly, Reductant Pump and Sensor Assembly harness is open or shorted, Reductant Pump and Sensor Assembly 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 546

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 Jul 24, 2021

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1040 GMC Description

The selective catalytic reduction system reduces Oxides of Nitrogen (NOx) emissions by injecting a metered amount of reductant into the exhaust gas stream entering the selective catalytic reduction catalyst. Within the selective catalytic reduction catalyst, the reductant reacts with the NOx to form nitrogen, carbon dioxide, and water vapor. Upstream and downstream NOx sensors provide the engine control module and the reductant control module via serial data. The Engine Control Module (ECM) controls the reductant injector duty cycle in response to changes in engine-out NOx levels. The reductant control module supplies system voltage to the reductant pump motor. The reductant control module controls the solenoid by grounding the control circuit. The reductant control module can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage. The Diagnostic Trouble Code (DTC) will be set when the reductant control module detects a motor pump phases shorted error.

OBDII Code P1040 GMC - Reductant Pump Control Circuit Shorted - AutoCodes.com — P1040 GMC Code - Reductant Pump Control Circuit Shorted

What does this mean?

What are the Possible Causes of the DTC P1040 GMC?

Faulty Reductant Pump and Sensor Assembly
Reductant Pump and Sensor Assembly harness is open or shorted
Reductant Pump and Sensor Assembly circuit poor electrical connection
Faulty Reductant Control Module

How to Fix the DTC P1040 GMC?

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 P1040 GMC 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 P1040 GMC 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 P1040 GMC Code

1. What are common symptoms of OBDII code P1040 GMC, Reductant Pump Control Circuit Shorted?

- The common symptoms include the check engine light illuminating on the dashboard, reduced engine performance, and potential issues with the vehicle's emissions system.

2. What causes the OBDII code P1040 GMC, Reductant Pump Control Circuit Shorted?

- The code can be triggered by a short circuit in the reductant pump control circuit, damaged wiring or connectors, or a malfunctioning reductant pump control module.

3. How can I diagnose the cause of OBDII code P1040 GMC, Reductant Pump Control Circuit Shorted?

- A thorough inspection of the wiring and connectors related to the reductant pump, as well as testing the reductant pump control module, can help pinpoint the issue.

4. Can driving with OBDII code P1040 GMC, Reductant Pump Control Circuit Shorted cause further damage?

- Continuing to drive with this code may lead to increased emissions, reduced fuel efficiency, and potential damage to the vehicle's emissions control system over time.

5. Are there any DIY repair tips for OBDII code P1040 GMC, Reductant Pump Control Circuit Shorted?

- If you have the necessary tools and expertise, you can inspect the wiring for damage, check the connectors for corrosion, and test the reductant pump control module for proper functionality.

6. Is it safe to continue driving with the check engine light on due to OBDII code P1040 GMC?

- It is generally not recommended to continue driving with the check engine light on, as unresolved issues can potentially lead to more serious problems and increased emissions.

7. How much does it typically cost to repair OBDII code P1040 GMC, Reductant Pump Control Circuit Shorted?

- The cost of repair can vary depending on the extent of the damage and whether any parts need to be replaced, but it may range from a few hundred to over a thousand dollars at a mechanic's shop.

8. Can resetting the OBDII code P1040 GMC, Reductant Pump Control Circuit Shorted make it go away permanently?

- Resetting the code may temporarily turn off the check engine light, but if the underlying issue is not addressed, the code is likely to reappear once the vehicle's onboard diagnostics detect the problem again.

9. How long does it take to repair OBDII code P1040 GMC, Reductant Pump Control Circuit Shorted?

- The repair time can vary depending on the complexity of the issue and the availability of parts, but it may take a few hours to a day for a mechanic to diagnose and fix the problem.

10. Will OBDII code P1040 GMC, Reductant Pump Control Circuit Shorted cause my vehicle to fail an emissions test?

- Yes, vehicles with unresolved emissions-related codes like P1040 are likely to fail emissions tests, so it's important to address the issue before taking the vehicle in for testing.