P0508 obd2 code is an indicator of IAC motor circuit fault

Checking P0508 fault code is to understand how your iac motor circuits affects your engine idle speed. Search also our obd2 code listings as shown below.

P0508 Engine IAC Control Ckt

iac motor wiring

This code refers to an erratic iac motor speed which could be surging or revving high and the ecm (engine computer) is trying to limit the injector spray to cut fuel and cut down or control idle speed via iac motor. As a precaution, always start the code testing by checking for engine vacuum leak which is the primary source of the failure. If there is no vacuum leak then proceed to test the iac wirings for shorts or open connections.

You can also measure the resistance of the iac motor wiring connections to the computer, iac relay or the iac motor itself. If the iac motor wiring connections are OK, proceed with the replacemenr of the iac motor. However, before replacing the iac motor; make sure to clean the throttle by spraying with carb cleaner to get rid of any stuck carbon deposit which could prevent idle control.

NOTE regarding IAC motor operation:

Please be warned that IAC motor works between a range of 0 at fully closed position to 160 at fully open position. What is required is the IAC motor setting to be at 40 motor steps at warm idle. It is also set on a curve based on parameter like coolant temperature which cooler to allow more steps to help in warming up the engine.

The ECU (engine control unit) will increase motor steps to adjust idle speed or to allow additional air through the TB (throttle body). The ISC (idle step control which is the amount of air that is bypassed the throttle plate) step count often increases at higher rpm and during wide open throttle operation.

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