DTC P1603: Engine Stall History; DTC P1605: Rough Idling [11/2021 - ]: Description

WARNING: This page is about a different car, the 2024 Lexus IS 500, 2023 Lexus IS 500, and 2022 Lexus IS 500. However, it is still accessible from the selected car via links, so may be relevant.

P1603

After starting the engine, this DTC is stored when the engine stops without the engine switch being operated.

Using the Techstream, the conditions present when the DTC was stored can be confirmed by referring to the freeze frame data. Freeze frame data records engine conditions when a malfunction occurs. This information can be useful when troubleshooting.

It is necessary to check if the vehicle has run out of fuel before performing troubleshooting, as this DTC is also stored when the engine stalls due to running out of fuel.

P1605

This DTC is stored if the engine speed drops below the set speed.

It is necessary to check if the vehicle ran out of fuel before performing troubleshooting, as this DTC is also stored when idling is unstable due to running out of fuel.

DTC No.	Detection Item	DTC Detection Condition	MIL	Memory
P1603	Engine Stall History	After monitoring for startability problems (P1604) finishes and 2 seconds or more have elapsed after starting the engine, with the engine running, the engine stops (the engine speed drops to 200 rpm or less) without the engine switch being operated for 0.5 seconds or more (1 trip detection logic).	Does not come on	DTC stored
P1605	Rough Idling	After 5 seconds or more have elapsed after starting the engine, with the engine running, the engine speed drops to 400 rpm or less (1 trip detection logic).	Does not come on	DTC stored

Trouble Area
Ignition system	Spark plug Ignition coil assembly
Fuel system	Fuel injector assembly (for port injection) Fuel injector assembly (for direct injection) Fuel pump (for low pressure side) Fuel pump (for high pressure side) Fuel pump control circuit Fuel line Purge VSV system Fuel quality (existence of foreign matter, degradation)
Intake and exhaust systems	Mass air flow meter sub-assembly Intake system (Air leaks or deposit accumulation) Throttle body with motor assembly Air fuel ratio sensor Heated oxygen sensor Camshaft timing control motor Camshaft timing oil control valve assembly Variable Valve Timing system (VVT system) Brake booster assembly
Other control systems	ECM Wire harness or connector Knock control sensor Engine coolant temperature sensor
Engine	Thermostat Engine assembly Engine mount
High load from another system	Air conditioning system Power steering system Electrical load signal system A/T system