AutoCodes – Buick – P2633 Buick

P2633 Buick Code - Fuel Transfer Pump Relay Control Circuit Low Voltage

Quick Answer

The Engine Control Module (ECM) enables the secondary fuel pump relay when the primary fuel tank is below approximately 50 liters (13.2 gallons) and will run until the primary tank is filled to approximately 70 liters (18.5 gallons) or until the secondary tank is empty. Common causes include Faulty Secondary Fuel Pump Relay, Secondary Fuel Pump Relay harness is open or shorted, Secondary Fuel 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: P2633 Buick indicates Fuel Transfer Pump Relay Control Circuit Low Voltage.
Common causes: Common causes include Faulty Secondary Fuel Pump Relay, Secondary Fuel Pump Relay harness is open or shorted, Secondary Fuel 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 313

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 01, 2021

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P2633 Buick Description

The Engine Control Module (ECM) enables the secondary fuel pump relay when the primary fuel tank is below approximately 50 liters (13.2 gallons) and will run until the primary tank is filled to approximately 70 liters (18.5 gallons) or until the secondary tank is empty. The ECM provides ignition positive voltage to the coil side of the fuel transfer pump relay. The ECM energizes the fuel transfer pump relay, which applies power to the fuel transfer pump.
The control module monitors the voltage on the fuel transfer pump relay control circuit. If the control module detects an incorrect voltage on the fuel transfer pump relay control circuit, a fuel transfer pump relay control Diagnostic Trouble Code (DTC) sets.

OBDII Code P2633 Buick - Fuel Transfer Pump Relay Control Circuit Low Voltage - AutoCodes.com — P2633 Buick Code - Fuel Transfer Pump Relay Control Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P2633 Buick?

Faulty Secondary Fuel Pump Relay
Secondary Fuel Pump Relay harness is open or shorted
Secondary Fuel Pump Relay circuit poor electrical connection
Faulty Engine Control Module (ECM)

How to Fix the DTC P2633 Buick?

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 P2633 Buick 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 P2633 Buick code?

Need more information on how to fix the P2633 Buick code? Get Access to Factory Service Manuals

Need Help with the 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 P2633 Buick Code

1. What does the OBDII code P2633 mean for a Buick?

P2633 indicates a low voltage condition in the fuel transfer pump relay control circuit, which affects the fuel transfer system's ability to function properly.

2. What are the common symptoms of code P2633 on a Buick?

Symptoms include difficulty starting the engine, engine stalling, reduced fuel efficiency, or the fuel gauge displaying inaccurate readings.

3. What causes the P2633 code to appear in a Buick?

The code may be triggered by a faulty fuel transfer pump relay, damaged wiring or connections in the circuit, a defective fuel transfer pump, or a weak battery.

4. Can driving with the P2633 code damage my Buick?

Driving with this code can lead to engine performance issues or cause the engine to stall, potentially leaving you stranded. Prompt diagnosis and repair are recommended.

5. How do I diagnose the P2633 code on my Buick?

Start by checking the fuel transfer pump relay, inspecting the wiring and connections for damage or corrosion, and testing the battery and alternator for proper voltage.

6. How do I fix the P2633 code on a Buick?

Repairs may include replacing the fuel transfer pump relay, repairing or replacing damaged wiring, cleaning corroded connections, or replacing the fuel transfer pump if necessary.

7. Is the P2633 code related to fuel delivery issues in a Buick?

Yes, this code directly relates to the fuel transfer system and may cause issues with delivering fuel from one tank or section to another.

8. What tools are needed to diagnose and repair P2633 on a Buick?

Youâ€™ll need an OBDII scanner, a multimeter for voltage testing, and basic tools for inspecting and replacing components like relays or wiring.

9. Can a weak battery cause the P2633 code on a Buick?

Yes, a weak or failing battery can lead to low voltage in the fuel transfer pump relay control circuit, triggering this code.

10. How much does it cost to fix the P2633 code on a Buick?

The cost varies depending on the underlying issue. Relay replacement might cost $50-$150, while fuel pump repairs or wiring work could range from $200 to $600 or more.