DTC P0506: Idle Air Control (IAC) Rpm Less Than Expected, Or P0507: Idle Air Control (IAC) Rpm More Than Expected (Esteem 1.6L & Swift)

NOTE: If any other DTCs are set, diagnose those DTCs first.

Turn engine off. Connect scan tool to Data Link Connector (DLC). Start engine and allow to reach normal operating temperature. Select DATA LIST mode on scan tool. Ensure IAC duty is within specification. See IDLE SPEED/IAC DUTY SPECIFICATIONS table. If idle speed and IAC duty are within specification, problem is intermittent or due to a faulty PCM. If idle speed is low, go to next step. If idle speed is high, go to step 4 .

IDLE SPEED/IAC DUTY SPECIFICATIONS

A/C OFF - RPM/IAC Duty Cycle ⁽¹⁾

A/C - ON RPM

A/T

750-850/3-20%

850-950

M/T

700-800/3-20%

850-950

⁽¹⁾	For vehicles operating at high altitude (6560 ft. or more), IAC duty cycle should be approximately 30 percent.

Check IAC valve operation referring to DTC P0505: IDLE AIR CONTROL (IAC) SYSTEM MALFUNCTION . If IAC valve does not operate as specified, repair as necessary and retest system. If IAC valve operates as specified, go to next step.
IAC duty (OFF) should be 30-70 percent (40-60 percent on high altitude vehicles). If IAC duty (OFF) is as specified, check for a clogged air passage or an excessive engine load. If IAC duty (OFF) is not as specified, replace PCM and retest system.
Check IAC valve operation referring to DTC P0505: IDLE AIR CONTROL (IAC) SYSTEM MALFUNCTION . If IAC valve does not operate as specified, repair as necessary and retest system. If IAC valve operates as specified, go to next step.
If IAC duty (OFF) is 3-97 percent, replace PCM. If IAC duty (OFF) is less than 3 percent or more than 97 percent, check for false air entering intake system from air intake system, PCV valve or EVAP canister purge control system. Repair as necessary and retest system.