P0505 · blink 33 – IDLE CONTROL SYSTEM MALFUNCTION

System: EFI 1NZ-FE/2NZ-FE
Dashboard light: Malfunction indicator lamp (Check Engine)
Check-engine blink code: 33
Applies to: 2NZ-FE 1.3 (PK XLi/GLi NZE120) and 1NZ-FE 1.5 (JDM NZE121/NZE124 Corolla/Fielder/Runx)
Description: IDLE CONTROL SYSTEM MALFUNCTION
Detection / symptoms: Detection: Idle speed continues to vary greatly from target speed (2 trip detection logic)
Possible causes: Open or short in ISC valve circuit; ISC valve; Engine ECU
What to check: Workshop check order (RM821E): CHECK HARNESS AND CONNECTOR -> CHECK HARNESS AND CONNECTOR(RSD CIRCUIT) -> INSPECT THLOTTLE BODY IDLE SPEED CONTROL VALVE ASSY -> CHECK HARNESS AND CONNECTOR(CHECK FOR OPEN AND SHORT BETWEEN
Confidence: high (official Toyota RM821E)

From the factory service material. Clear the code and test-drive to confirm it returns. Search all fault codes · Common problems · Warning lights