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P0B01 Cadillac Code - Auxiliary Transmission Fluid Pump Low Current

Quick Answer

The Diagnostic Trouble Code (DTC) P0B01 indicates a low current condition in the auxiliary transmission fluid pump, which is a critical component in hybrid and electric vehicles. Common causes include Faulty Transmission Fluid Pump Electric/AuxiliaryTransmission Fluid Pump Electric/Auxiliary harness is open or shortedTransmission Fluid Pump Electric/Auxiliary circuit poor electrical connectionFaulty Power Inverter ModuleWorn or damaged motor control modules. 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
P0B01 Cadillac indicates Auxiliary Transmission Fluid Pump Low Current.
Common causes
Common causes include Faulty Transmission Fluid Pump Electric/AuxiliaryTransmission Fluid Pump Electric/Auxiliary harness is open or shortedTransmission Fluid Pump Electric/Auxiliary circuit poor electrical connectionFaulty Power Inverter ModuleWorn or damaged motor control modules.
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.
What is this?
Table of contents Created and updated by William Orellana on Nov 05, 2025
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Code P0B01 Cadillac Description

The Diagnostic Trouble Code (DTC) P0B01 indicates a low current condition in the auxiliary transmission fluid pump, which is a critical component in hybrid and electric vehicles. The auxiliary transmission fluid pump is responsible for circulating transmission fluid to ensure proper lubrication and cooling of the transmission system. This pump is controlled by the hybrid/EV powertrain control module 1, which communicates with the power inverter module to manage the pump's operation. When the current detected in one or more of the motor phases (U, V, W) falls below 1 ampere, the system triggers the P0B01 code.
OBDII Code P0B01 Cadillac - Auxiliary Transmission Fluid Pump Low Current
P0B01 Cadillac Code - Auxiliary Transmission Fluid Pump Low Current

Common Causes of P0B01 Cadillac

  1. Faulty Transmission Fluid Pump Electric/Auxiliary
  2. Transmission Fluid Pump Electric/Auxiliary harness is open or shorted
  3. Transmission Fluid Pump Electric/Auxiliary circuit poor electrical connection
  4. Faulty Power Inverter Module
  5. Worn or damaged motor control modules

Symptoms of P0B01 Cadillac

  1. Engine Light ON (or Service Engine Soon Warning Light)
  2. Erratic or harsh shifting during gear changes
  3. Decreased fuel efficiency
  4. Transmission overheating or slipping
  5. Unusual noises from the transmission area

How to Fix P0B01 Cadillac

  1. Perform a visual inspection of the auxiliary transmission fluid pump and its wiring harness for damage or disconnections.
  2. Test the current draw of the pump motor to confirm if it is below the required threshold.
  3. Check for any fault codes in the power inverter module and hybrid/EV powertrain control module to identify related issues.
  4. If necessary, replace the faulty auxiliary transmission fluid pump or repair the wiring harness.
  5. Clear the DTC and perform a road test to ensure proper operation and verify that the engine light does not reappear.

Cost to Fix P0B01 Cadillac

The cost to diagnose and repair the P0B01 code typically ranges from $200 to $1,200, depending on the specific issue identified. This includes parts such as the auxiliary transmission fluid pump, which can cost between $150 to $600, and labor, which varies based on shop hourly rates (generally $80–$150/hr). Dealerships may charge more, while independent shops often offer lower rates. The total cost can also be influenced by the make and model of the vehicle and the complexity of the repair needed.

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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.

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