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High idle at startup Honda

Fix high idle at startup on my Honda

Honda vehicles may exhibit a high idle at startup that can run as high as 2,000 RPM. As the engine warm, it idles down to around 1,500. But that’s still too high. On ‘90’s and early 2000’s vehicles, Honda used an idle air bypass valve that’s controlled by a thermo wax pellet.

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Thermo controlled idle air bypass valve

Coolant runs through the idle control valve and as the coolant heats and melts the was, the valve gradually decreases air bypassing around the throttle plate. Coolant debris can build up on the thermo mechanism, causing it to malfunction and resulting in a High idle at startup Honda.

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Some shops have had luck cleaning the valve. Others have found it’s more efficient to simply replace it. Disconnect the coolant tubes (be prepared to take a bath in coolant) and remove the valve. Inspect the ports for debris buildup. Then clean or replace the valve

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