AutoCodes – Generic – P2633

P2633 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 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 8,735

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

What does this mean?

What are the Possible Causes of the DTC P2633?

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?

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 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 code?

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

Need Help with the Code?

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Information for Specific Makes

P2633 Audi — Fuel Pump 'B' Control Circuit Low
P2633 Buick — Fuel Transfer Pump Relay Control Circuit Low Voltage
P2633 Cadillac — Fuel Transfer Pump Relay Control Circuit Low Voltage
P2633 Chevrolet — Fuel Transfer Pump Relay Control Circuit Low Voltage
P2633 Dodge — Fuel Pump 'B' Control Circuit Low
P2633 Ford — Fuel Pump 'B' Control Circuit Low
P2633 GMC — Fuel Transfer Pump Relay Control Circuit Low Voltage
P2633 Lincoln — Fuel Pump 'B' Control Circuit Low
P2633 Mercury — Fuel Pump 'B' Control Circuit Low
P2633 Volkswagen — Fuel Pump 'B' Control Circuit Low

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.