AutoCodes – Chevrolet – P2603 Chevrolet

P2603 Chevrolet Code - Auxiliary Coolant Pump Circuit High

Quick Answer

The auxiliary coolant pump and cooling fan system provides a measure of prevention against fuel vaporization due to excessive engine temperatures. Common causes include Faulty Auxiliary Coolant Pump Relay, Blocked pump control passage, Faulty Auxiliary Coolant Pump. 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: P2603 Chevrolet indicates Auxiliary Coolant Pump Circuit High.
Common causes: Common causes include Faulty Auxiliary Coolant Pump Relay, Blocked pump control passage, Faulty Auxiliary Coolant Pump.
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 1,625

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 Jan 19, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P2603 Chevrolet Description

The auxiliary coolant pump and cooling fan system provides a measure of prevention against fuel vaporization due to excessive engine temperatures. The Engine Control Module (ECM) commands the auxiliary or after boil coolant pump ON when the engine coolant temperature exceeds a calibrated value after engine shut down. The ECM applies ground to the coil side of the auxiliary pump relay. This energizes the coil and applies voltage directly to the pump motor through the switch side of the relay. When the auxiliary coolant pump is activated, coolant is drawn from radiator and pumped into the engine through a tee in the engine coolant inlet pipe. As the colder temperature coolant is drawn into the engine warmer coolant is expelled from the engine and back to the radiator. Removing high temperature coolant from the engine after shut down helps prevent vaporization of the fuel that remains in the fuel injectors and fuel rail during a hot soak.

OBDII Code P2603 Chevrolet - Auxiliary Coolant Pump Circuit High - AutoCodes.com — P2603 Chevrolet Code - Auxiliary Coolant Pump Circuit High

What does this mean?

What are the Possible Causes of the DTC P2603 Chevrolet?

Faulty Auxiliary Coolant Pump Relay
Blocked pump control passage
Faulty Auxiliary Coolant Pump
Auxiliary Coolant Pump harness is open or shorted
Auxiliary Coolant Pump circuit poor electrical connection

How to Fix the DTC P2603 Chevrolet?

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 P2603 Chevrolet 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 P2603 Chevrolet Code

1. What are the common symptoms of OBDII code P2603 in a Chevrolet related to the Auxiliary Coolant Pump Circuit High?

- Common symptoms include the Check Engine Light illuminating, overheating issues, and potential reduced engine performance.

2. What could be the possible causes of OBDII code P2603 in a Chevrolet indicating an Auxiliary Coolant Pump Circuit High?

- The code may be triggered by a faulty auxiliary coolant pump, damaged wiring or connectors in the coolant pump circuit, or a malfunctioning coolant pump control module.

3. How can I diagnose the issue causing OBDII code P2603 in my Chevrolet for the Auxiliary Coolant Pump Circuit High?

- Diagnosing the problem involves checking the auxiliary coolant pump for proper operation, inspecting the wiring and connectors for any damage, and testing the coolant pump control module for functionality.

4. Can I continue driving my Chevrolet with OBDII code P2603 indicating an Auxiliary Coolant Pump Circuit High?

- It is not recommended to drive your vehicle with this code, as it can lead to potential engine overheating and damage. It is best to address the issue promptly.

5. Is it possible to reset OBDII code P2603 related to the Auxiliary Coolant Pump Circuit High in my Chevrolet without fixing the underlying issue?

- Resetting the code without addressing the root cause will not solve the problem. It is essential to diagnose and repair the issue causing the code to prevent further complications.

6. Are there any DIY repair tips for fixing OBDII code P2603 in a Chevrolet with an Auxiliary Coolant Pump Circuit High?

- DIY repair tips include checking the coolant pump fuse, inspecting the coolant pump wiring for damage, and ensuring the coolant pump is functioning correctly.

7. How much can I expect to pay for repairing OBDII code P2603 in a Chevrolet due to an Auxiliary Coolant Pump Circuit High?

- The cost of repair can vary depending on the exact cause of the issue. It is recommended to consult a mechanic for a proper diagnosis and cost estimate.

8. Can a faulty thermostat be a potential cause of triggering OBDII code P2603 in a Chevrolet related to the Auxiliary Coolant Pump Circuit High?

- While a faulty thermostat can lead to overheating issues, it is not a direct cause of OBDII code P2603. The code is typically related to specific components in the coolant pump circuit.

9. Will addressing OBDII code P2603 in my Chevrolet Auxiliary Coolant Pump Circuit High improve fuel efficiency?

- Resolving the code may help optimize engine performance and overall efficiency, but the direct impact on fuel efficiency may vary depending on the specific issue causing the code.

10. How long does it typically take to repair OBDII code P2603 in a Chevrolet associated with an Auxiliary Coolant Pump Circuit High?

- The repair time can vary based on the complexity of the issue and the availability of parts. It is advisable to consult a professional mechanic for an accurate estimate of the repair duration.