Electric Coolant Pump

Circulates coolant on demand rather than in proportion to engine speed, which is the flaw a belt-driven pump cannot escape — an engine needs most cooling crawling in traffic and least at a motorway cruise, and a belt pump has it backwards. Its more consequential job is running when the engine is not: a few minutes of run-on after shutdown keeps coolant moving through a turbocharger bearing housing that is still soaking heat, which is what stops the oil in it baking onto the shaft. It also supplies the heater matrix while a stop-start system or a hybrid has the engine switched off. Not self-priming, so an air pocket left after a coolant refill stops one pumping while it spins happily — and running dry is what destroys it.

Also known as: auxiliary water pump, auxiliary coolant pump, electric water pump, turbo run-on pump, circulation pump, aux pump

Referenced by 149 codes

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Codes involving this component (149)

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