AutoCodes – GMC – P023C GMC

P023C GMC Code - Charge Air Cooler Coolant Pump Relay Control Circuit High

Quick Answer

The supercharger intercooler relay is a normally open relay. Common causes include Faulty Charge Air Cooler Coolant Pump Relay, Charge Air Cooler Coolant Pump Relay harness is open or shorted, Charge Air Cooler Coolant Pump Relay 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: P023C GMC indicates Charge Air Cooler Coolant Pump Relay Control Circuit High.
Common causes: Common causes include Faulty Charge Air Cooler Coolant Pump Relay, Charge Air Cooler Coolant Pump Relay harness is open or shorted, Charge Air Cooler Coolant Pump Relay 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 59

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 Oct 11, 2025

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P023C GMC Description

The supercharger intercooler relay is a normally open relay. The relay armature is held in the open position by spring tension. The ignition 1 voltage is supplied directly to the relay coil and to the armature contact when the ignition is ON, or the engine is running. The Engine Control Module (ECM) supplies the ground path to the relay coil control circuit via an internal integrated circuit called an output driver module. When the engine is running, the ECM commands the relay ON, and the relay coil creates an electromagnetic field. This electromagnetic field overcomes the spring tension and pulls the armature contact into the stationary contact of the relay load circuit. The closing of the relay contacts allow current to flow from the battery to the supercharger intercooler pump. When the ignition switch is turned to the OFF position, power is interrupted to the output driver module in the ECM and the relay electromagnetic field collapses. This allows the spring tension to separate the relay armature contact from the relay load circuit contact, which interrupts current flow to the supercharger charge air cooler coolant pump.
If the ECM detects an improper voltage on the pump relay control circuit this DTC sets.

OBDII Code P023C GMC - Charge Air Cooler Coolant Pump Relay Control Circuit High - AutoCodes.com — P023C GMC Code - Charge Air Cooler Coolant Pump Relay Control Circuit High

What does this mean?

What are the Possible Causes of the DTC P023C GMC?

Faulty Charge Air Cooler Coolant Pump Relay
Charge Air Cooler Coolant Pump Relay harness is open or shorted
Charge Air Cooler Coolant Pump Relay circuit poor electrical connection

How to Fix the DTC P023C 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 P023C 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.

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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.