Coolant Pump B Underspeed

Where it lives

For P2B9F, the description names the pump as the part involved.

Check these first

• A wear or drag condition slowing coolant pump B
• A failing coolant pump B motor
• A restriction in the coolant loop limiting pump B speed
• Low coolant or air at the pump B inlet

What to do next

1. Scan all modules and read the coolant pump B commanded and actual speed
2. Check the coolant level and bleed air at pump B
3. Inspect the coolant loop for a restriction or kink
4. Command coolant pump B to full speed and compare to actual
5. Replace coolant pump B if it stays underspeed with a clear loop
6. Clear the code and retest

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