Auxiliary Transmission Fluid Pump Motor Phase W Current Fault
The P0B06 code indicates a malfunction in the auxiliary transmission fluid pump motor phase W circuit. This pump is responsible for circulating transmission fluid to maintain lubrication and cooling, especially during start-stop events or when the engine is off. The diagnostic trouble code (DTC) is set when the powertrain control module (PCM) detects an abnormal current reading in phase W of the pump motor, which can be due to electrical issues, mechanical failure, or control module problems.
01. Most Common Causes
- Faulty auxiliary transmission fluid pump motor
- Open or shorted wiring in phase W circuit
- Damaged pump motor connector or terminals
- Failed transmission control module (TCM) or PCM
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Transmission slipping or harsh shifting
- Reduced fuel economy
- Transmission overheating or warning messages
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Visually inspect the auxiliary pump wiring and connector for damage, corrosion, or loose connections.
Step 3: Test the pump motor resistance and continuity in phase W using a multimeter.
Step 4: Check the pump motor operation by applying battery voltage directly (if safe) or using a scan tool to command the pump.
Step 5: If wiring and motor are okay, test the TCM/PCM outputs and consider reprogramming or replacement.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as the auxiliary pump failure can lead to transmission overheating and damage. Have the vehicle inspected promptly.
How much does it cost to fix?▼
Repair costs vary: diagnosing the issue typically costs $50-$150. Replacing the pump motor can range from $200-$600, while wiring repairs may be $100-$300.