P2B9C: Coolant Pump A Stuck/Stalled

What it means

Coolant pump A reports a stuck/stalled condition. Coolant circulation through the affected loop cannot be commanded reliably.

At a glance

• Usually lights the check-engine light
• The engine or gearbox may go into limp mode

How it works

Coolant pump A circulates coolant through its assigned cooling loop, and the control module monitors whether the pump responds to commands. P2B9C sets when pump A is detected as mechanically stuck or stalled and cannot provide the expected circulation.

Common causes

Most likely first.

1. Pump impeller jammed by debris
2. Motor seized

Symptoms

• Check-engine light
• Coolant temperature warning or rising temperature gauge
• Reduced engine power

How to diagnose it

1. Record freeze-frame data and pump command or status with a scan tool, and check for a coolant temperature warning or rising temperature.
2. With the engine cool, inspect the coolant level and look for leaks or visible debris that could restrict pump A's loop.
3. Identify pump A from the vehicle's service information, then inspect its connector and wiring for damage, looseness, or corrosion.
4. Use the scan tool's available pump command test and check for evidence that pump A responds or coolant circulates.
5. If the electrical supply and command are present but pump A does not operate, inspect the pump for binding or a jammed impeller and compare test results with the manufacturer's specification.

Common fixes

• Restore the correct coolant level and repair any leak found, following the vehicle's specified coolant procedure.
• Repair a loose or damaged pump A connector or wiring.
• Clear debris or a restriction from pump A's coolant loop if confirmed.
• Replace pump A if it remains stuck or stalled despite a sound circuit.

Can I keep driving?

A rising temperature gauge or coolant warning makes continued driving unsafe; stop in a safe place and switch off the engine to limit overheating damage. Do not open the cooling system while hot, and arrange assistance if temperature does not return to normal.