What Does P2633 Mean?
The fuel pump 'B' control circuit voltage is below the expected threshold. The ECM has detected that the signal or voltage in the circuit controlling the secondary or auxiliary fuel pump is too low, indicating a potential short to ground or driver circuit failure.
Common Causes
35%
Damaged or chafed wiring creating a short to ground in the fuel pump control circuit
30%
Failed fuel pump driver module or ECM internal driver circuit
20%
Corroded or damaged electrical connector at fuel pump or control module
15%
Faulty fuel pump 'B' with internal short to ground
Diagnostic Steps
1
Step 1: Visually inspect all wiring and connectors in the fuel pump 'B' control circuit for damage, corrosion, or signs of shorting
2
Step 2: Disconnect fuel pump 'B' connector and measure resistance to ground on the control wire from the ECM/driver module side
3
Step 3: Check voltage supply and ground circuits at the fuel pump connector with key on
4
Step 4: Test the fuel pump driver module output signal using a digital multimeter or oscilloscope
5
Step 5: If all wiring checks good, test fuel pump 'B' resistance and compare to specifications
Estimated Repair Cost
$150 - $800
Parts + labor, varies by vehicle and location
The fuel pump 'B' control circuit voltage is below the expected threshold. The ECM has detected that the signal or voltage in the circuit controlling the secondary or auxiliary fuel pump is too low, indicating a potential short to ground or driver circuit failure.
The most common cause of P2633 (Fuel Pump "B" Control Circuit Low) is: Damaged or chafed wiring creating a short to ground in the fuel pump control circuit
Typical repair costs for P2633 range from $150 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle may experience reduced power, hesitation, or stalling under high fuel demand conditions. May be drivable but should be repaired promptly to prevent complete fuel delivery failure.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2633 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel System
Difficulty
Type
Generic (SAE)
Recommended Tools
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