Engine-CodesGMC – P1048 2018 GMC Sierra

P1048 2018 GMC Sierra Code - Reductant Injector High Control Circuit Low Voltage

Quick Answer

The P1048 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates a problem with the reductant injector high control circuit having low voltage. Common causes include Faulty reductant injector control module, Wiring or connector issues in the control circuit, Low DEF fluid level. 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
P1048 2018 GMC Sierra indicates Reductant Injector High Control Circuit Low Voltage.
Common causes
Common causes include Faulty reductant injector control module, Wiring or connector issues in the control circuit, Low DEF fluid level.
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.
Table of contents Created and updated by William Orellana on Sep 16, 2024
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Code P1048 2018 GMC Sierra Description

The P1048 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates a problem with the reductant injector high control circuit having low voltage. In modern diesel vehicles, a reductant injector is used to introduce a urea-based solution (commonly known as diesel exhaust fluid or DEF) into the exhaust stream to reduce harmful emissions. The reductant injector control module regulates the operation of the injector based on various sensor inputs.

OBDII Code P1048 2018 GMC Sierra - Reductant Injector High Control Circuit Low Voltage
P1048 2018 GMC Sierra Code - Reductant Injector High Control Circuit Low Voltage

Common Causes of P1048 2018 GMC Sierra

  1. Faulty reductant injector control module
  2. Wiring or connector issues in the control circuit
  3. Low DEF fluid level
  4. Electrical system malfunctions
  5. Corrosion or damage to the injector components

Symptoms of P1048 2018 GMC Sierra

  1. Illuminated check engine light
  2. Reduced fuel efficiency
  3. Increased emissions
  4. Engine misfires
  5. Reduced engine performance

How to Fix P1048 2018 GMC Sierra

  1. Diagnose the specific cause of the low voltage in the reductant injector control circuit using a diagnostic scanner.
  2. Inspect the wiring harness and connectors for any damage or corrosion, repairing or replacing as necessary.
  3. Test the reductant injector control module for proper operation and replace if faulty.
  4. Verify the DEF fluid level and quality, topping up or replacing as needed.
  5. Clear the DTC and reset the check engine light after completing repairs.

Cost to Fix P1048 2018 GMC Sierra

The typical repair costs for addressing a P1048 code on a 2018 GMC Sierra can vary depending on the specific cause of the issue. Parts such as a reductant injector control module or wiring harness may range from $200 to $500, while labor costs can add another $100 to $300. Overall, the total repair cost could fall between $300 and $800. It's important to note that diagnosis time and labor rates at auto repair shops can fluctuate, so it's advisable to check with local providers for a more accurate estimate.

Tech Notes for P1048 2018 GMC Sierra









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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.

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