P056A - Low Temperature Coolant Pump Control Circuit Low
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P056A is a generic diagnostic trouble code indicating that the Engine Control Module (ECM) has detected a low voltage condition in the control circuit for the Low Temperature (Secondary) Coolant Pump. This electric pump is critical for cooling the intake charge in turbocharged or supercharged engines. The ECM monitors the feedback or sense line of the pump driver circuit. If the voltage remains below the calibrated threshold while the pump is commanded ON, it signifies a short to ground or an internally seized pump motor pulling down the circuit. This failure triggers a reduction in boost pressure (Limp mode) to prevent engine damage from high Intake Air Temperatures (IAT).
Possible Causes
Short to ground in the coolant pump control wiring harness.
Faulty low-temperature coolant pump (internal electrical short).
Corroded or loose connectors at the pump or ECM.
Faulty coolant pump relay or internal ECM driver failure.
Symptoms
Recommended Solution
Workflow
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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