Trouble with a 2000 Honda Civic

[crazydrive]

My friend's asking for any suggestions on his problem.

He had just replaced his coolant the other day and his car was running fine for two days when the check engine light came on. The night before the replacement, the cars' RPMs started going erratic and it would go up and down from 1 to about 2.5 non-stop. When he checked that night, he noticed a little smoke was coming from around the headers and shut his car off. The following day, he returned to check his fluids and saw that he was running low on engine coolant so he put some and the car ran fine. But two days after the replacement of the coolant, the check engine light came on. We're both stumped on what to do. Any ideas would be welcome.


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[Sterling_Six]

Originally Posted by crazydrive

My friend's asking for any suggestions on his problem.

He had just replaced his coolant the other day and his car was running fine for two days when the check engine light came on. The night before the replacement, the cars' RPMs started going erratic and it would go up and down from 1 to about 2.5 non-stop. When he checked that night, he noticed a little smoke was coming from around the headers and shut his car off. The following day, he returned to check his fluids and saw that he was running low on engine coolant so he put some and the car ran fine. But two days after the replacement of the coolant, the check engine light came on. We're both stumped on what to do. Any ideas would be welcome.


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WTB:exhaust systems

Hello and good day to you:

Have you gone to your local Auto Repair Store...like AutoZone, or Advance Auto to have the OBDII Codes read for the CEL (check Engine Lite) Codes??

First have the Codes Read....and then please advise further....

How ever this sounds like a classic Head Gasket Failure....

Please Advise what year..make..and model of this vehicle is...

Thank you and keep in touch...

[crazydrive]

We got the code pulled out and it said p1509 idle air control valve circuit fault. What does it mean? The car is a 2000 Honda Civic.

[Sterling_Six]

Hello and good day:

May I first suggest that you buy a "Haynes Repair Manual" for this Vehicle, this will give you a better Idea of where the IAC is located on you Honda Civic.

An IAC (idle air control) motor is designed to adjust the engine idle RPM speed by opening and closing an air bypass passage inside the throttle body. The car computer or ECM (electronic control module) receives information from various sensors and will output signals to adjust the IAC motor in or out to adjust engine idle speed by controlling engine idle air. An IAC motor can fail one of two ways, either the motor short circuits and stops working or the motor will develop high resistance and cause the IAC control motor to react slowly, either failure will cause the engine to stall at idle. When a trouble code scan is performed it sometimes won't always detect a failed or weak IAC motor. To check the IAC motor remove the unit, with the wires connected turn the key to the "on" position without starting the engine, the IAC should move in or out. If the IAC motor does nothing it has probably failed, replace it with a new unit and recheck system. note: while the IAC motor is removed clean (use aerosol carburetor cleaner) the passages the IAC uses to control idle air speed.


Idle Air Control Valve (appearance will vary)



Please follow these Links:

How Does an Idle Air Control Valve Work? IAC

DIAGNOSTIC TROUBLE CODE (DTC) 0505 IDLE AIR CONTROL VALVE (IACV) CIRCUIT FAULT

Check Engine Light - Lonewolf Online

what is a IAC valve - Google Search