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Home >> Scion >> 2013 >> xB Standard Trans >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (Diagnostic Codes (P0420-P1605)) >> SFI System >> DTC P050A: Cold Start Idle Air Control System Performance >> Monitor Description
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Monitor Description

This monitor will run when the engine is started at an engine coolant temperature of -10 to 50°C (14 to 122°F). The DTC will be stored after the engine idles for 13 seconds (2 trip detection logic).

The DTC is designed to monitor the idle air control at cold start. When the engine is started at an engine coolant temperature of lower than 50°C (122°F), the ECM measures the accumulated mass air flow at engine idling. If it does not reach the specified level within 10 seconds, the ECM interprets this as a malfunction. The MIL is illuminated and a DTC is stored when the malfunction is detected in consecutive driving cycles (2 trip detection logic).

The ETCS (Electronic Throttle Control System) controls the idle speed. The ETCS operates the throttle actuator to open and close the throttle valve, and adjusts the intake air amount to achieve the target idle speed.

NOTE:

When the negative battery terminal is disconnected during inspections or repairs, the ISC (Idle Speed Control) learning values are cleared. This DTC cannot be stored with the ISC learning values cleared.

HINT: 

The ISC learning is performed when the engine is warmed up and has been idling for 5 minutes.

Fig 1: View Of Engine Coolant Temperature Graph
GTY161291Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
DTC No. DTC Detection Condition Trouble Area
P050A Insufficient mass air flow at cold start
(2 trip detection logic)
  • Throttle body
  • Mass air flow meter
  • PCV system
  • Air cleaner filter element
  • Intake system
  • VVT system
  • ECM
  • Wire harness or connector