DTC P1605: Rough Idling [03/2019 - 11/2022]: Description

WARNING: This page is about a different car, the 2022 Toyota Corolla, 2021 Toyota Corolla, 2020 Toyota Corolla, and 2019 Toyota Corolla. However, it is still accessible from the selected car via links, so may be relevant.

This DTC is stored if the combustion state of any cylinder is unstable.

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 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	Note
P1605	Rough Idling	When idling with the accelerator pedal released and the vehicle stopped, this item detects when the combustion is unstable from the sudden changes in engine speed between the cylinders. Detection for 2 to 10 seconds according to the combustion state. (1 trip detection logic).	Does not come on	DTC stored	DTC for Mexico Models - Applies

Trouble Area
Ignition system	Spark plug Ignition coil assembly
Fuel system	Fuel injector assembly Fuel pump 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 assembly Air fuel ratio sensor Heated oxygen sensor Camshaft timing oil control valve assembly VVT system (Variable Valve Timing system)
Other control systems	ECM Wire harness or connector Knock control sensor Engine coolant temperature sensor
Engine	Thermostat Engine assembly
High load from another system	Air conditioning system Power steering system Electrical load signal system CVT system