AutoCodes – GMC – P2039 GMC

P2039 GMC Code - Reductant Injection Air Pressure Sensor 'A' Circuit Low

Quick Answer

The reductant system uses a selective reduction catalyst to improve exhaust emissions and fuel efficiency by injecting a reductant into the exhaust system. Common causes include Faulty Reductant Injection Air Pressure Sensor, Reductant Injection Air Pressure Sensor harness is open or shorted, Reductant Injection Air Pressure 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: P2039 GMC indicates Reductant Injection Air Pressure Sensor 'A' Circuit Low.
Common causes: Common causes include Faulty Reductant Injection Air Pressure Sensor, Reductant Injection Air Pressure Sensor harness is open or shorted, Reductant Injection Air Pressure 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 1,481

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 Aug 04, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P2039 GMC Description

The reductant system uses a selective reduction catalyst to improve exhaust emissions and fuel efficiency by injecting a reductant into the exhaust system. The reductant also referred to as diesel exhaust fluid is a 32.5% solution of urea in deionized water. The reductant system reduces Nitrogen Oxides (NOx) present in the exhaust stream to nitrogen and water.
The Reductant Injection Air Pressure Sensor sends voltage reading information to the Powertrain Control Module (PCM). The PCM interprets these readings as pressure or exhaust gas temperature. The code is set when the voltage sent from the sensor to the PCM is out of factory specifications.

OBDII Code P2039 GMC - Reductant Injection Air Pressure Sensor 'A' Circuit Low - AutoCodes.com — P2039 GMC Code - Reductant Injection Air Pressure Sensor 'A' Circuit Low

What does this mean?

What are the Possible Causes of the DTC P2039 GMC?

Faulty Reductant Injection Air Pressure Sensor
Reductant Injection Air Pressure Sensor harness is open or shorted
Reductant Injection Air Pressure Sensor circuit poor electrical connection
Faulty Reductant Pump Assembly

How to Fix the DTC P2039 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 P2039 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 P2039 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.