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Home >> Toyota >> 2015 >> Prius Two >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (Diagnostic Codes (P0300-P0657)) (Except Plug-In) >> SFI System >> DTC P050A: Cold Start Idle Air Control System Performance [08/2014 - ] >> 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 can be set 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 idle. 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 set when the malfunction is detected in consecutive driving cycles (2 trip detection logic).

The electronic throttle control system controls the idle speed. The electronic throttle control system operates the throttle actuator to open and close the throttle valve, and adjusts the intake air amount to achieve the target idle speed.

NOTE:

The idle speed control learned values are cleared by performing a learned value reset. Idle speed control learning needs to be performed before this DTC can be stored. To perform idle speed control learning, the engine must be warmed up by allowing it to idle for 5 minutes. For idle speed control learning to be successful, when the engine is started to warm it up, there must be at least 10 seconds of idling with the coolant temperature less than 50°C (122°F) before allowing it to continue running for the 5 minutes learning period.

Fig 1: P050A Detection Logic Graph
GTY317890Courtesy 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 assembly
  • Mass air flow meter sub-assembly
  • PCV hose
  • Air cleaner filter element sub-assembly
  • Intake system
  • VVT system
  • EGR valve assembly
  • Wire harness or connector
  • ECM