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code reader says cat not ready,o2s not ready(new o1 sensor,ho2s sensor not ready,. Throttle rpm goes from 1000 to 3000 rpm without incremental control in-between. Coil in iac checked 28ohms each leg,cleaned rotary valve and went from 1-2 thousand slow pulsing rpm to 50 rpm pulsing. If checking supply voltage, is iac valve the likely culprit or map sensor? disconnected battery,then pushed horn button and brake pedal but cannot eliminate the 1509 code with erase function. These problems started as result of defective alternator allowing battery to completely drain at night waiting for tow. A slow recharge allowed a recharge and engine started with noticeable multi-codes and problems. P1509 and NR indications are left to correct.

Vehicle: 1997 Honda LX auto 1.6 liter

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P1509  Idle air control valve circuit,

When you have a code reader that says 02 not ready, catalytct not ready, you are in the I/M readiness monitor menu.This is for smog evaluations,or a emission test. If the throttle goes from 1000 to 3000 RPM check for vacuum leaks, especially  a open EGR valve or any vacuum leak., The IAC uses coolant to flow over a bimetal coil,which causes the coil to open,or close in response to coolant temperature. In case of electrical failure the valve will default to a halfway setting this will cause the idle to boost up. This is why you need to check for vacuum leaks, The IAC is more likey the culprit, If you have a vacuum leak at all time the MAP will code up.
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Thx for your time.  I will use your information as I proceed with repair procedure!  Fiberglass1

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