2ZR-FAE (ENGINE CONTROL): SFI SYSTEM: P1605; Rough Idling; 2020 - 2023 MY Corolla [03/2019

Last Modified: 07-31-2024	6.11:8.1.0	Doc ID: RM100000001HT5L
Model Year Start: 2020	Model: Corolla	Prod Date Range: [03/2019 - 11/2022]
Title: 2ZR-FAE (ENGINE CONTROL): SFI SYSTEM: P1605; Rough Idling; 2020 - 2023 MY Corolla [03/2019 - 11/2022]

DTC

P1605

Rough Idling

DESCRIPTION

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

CAUTION / NOTICE / HINT

HINT:

DTC P1605
- In contrast to conventional DTCs for components, circuits and systems, DTC P1605 is used to estimate the malfunctioning area from problem symptoms and Freeze Frame Data in response to symptoms such as "rough idling", "strong engine vibrations", etc.
  Such problem symptoms can occur even in the following conditions:
  - Driving with long-stored fuel (fuel that has remained in the tank for long periods of time)
  - Using fuel not acclimated to the climate during a change of seasons
  - Temporarily using low-quality fuel (fuel that contains water or has poor fuel properties)
- As DTCs may be stored when an Active Test or learning is performed, make sure to clear the DTCs before returning the vehicle to the customer.
- If any other DTCs are output, perform troubleshooting for those DTCs first.
FREEZE FRAME DATA
- Read Freeze Frame Data using the Techstream. Freeze frame data records engine conditions when a malfunction occurs. This information can be useful when troubleshooting.
- When confirming the Freeze Frame Data, be sure to check all 5 sets of Freeze Frame Data.
  Click here
- When confirming Freeze Frame Data, if there are multiple items related to the cause of the malfunction, perform troubleshooting for all related items.
- Try to operate the vehicle under the conditions recorded in the Freeze Frame Data which were present when the malfunction occurred. Confirm the data at this time and the data when the engine is idling (engine warmed up, no load, and shift lever in D or N) and compare this data with the Freeze Frame Data.
PRECAUTIONS
- Inspections take into account the fact that the malfunction may not have recurred and place emphasis on checking the vehicle conditions present at the time when the malfunction occurred.
- When performing inspections, jiggle the relevant wire harnesses and connectors in an attempt to reproduce malfunctions that do not always occur.

PROCEDURE

1.	CHECK FOR ANY OTHER DTCS OUTPUT

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

(e) Read the DTCs.

Powertrain > Engine and ECT > Trouble Codes

Result	Proceed to
Only DTC P1605 is output	A
DTCs other than P1605 are output	B

HINT:

If any DTCs other than P1605 is output, troubleshoot those DTCs first.
Using Freeze Frame Data, confirm the conditions the moment the DTC was stored and after the DTC was stored. This information can be useful when troubleshooting.

GO TO DTC CHART

2.	READ FREEZE FRAME DATA (ROUGH IDLE, PLURAL CYLINDERS ROUGH IDLE, ROUGH IDLE STATUS, COMPRESSION LEAKAGE COUNT)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(d) Using the Techstream, confirm the vehicle conditions recorded in the Freeze Frame Data which were present when the DTC was stored.

Powertrain > Engine and ECT > DTC(P1605) > Freeze Frame Data

Tester Display
Compression Leakage Count
Rough Idle Status
Plural Cylinders Rough Idle
Rough Idle #1
Rough Idle #2
Rough Idle #3
Rough Idle #4

Freeze Frame Data Item for DTC P1605			Suspected Area	Action	Proceed to
Rough Idle #1 to #4 Plural Cylinders Rough Idle	Rough Idle Status	Compression Leakage Count	Suspected Area	Action	Proceed to
"One of Rough Idle #1 to #4 is ON" and "Plural Cylinders Rough Idle is OFF"	"Misfire"	4 or less	Spark plug Ignition coil assembly Fuel injector assembly	Go to Rough Idling (from step 7)	A
	One of the following is displayed: Continuous poor combustion Intermittent poor combustion Low frequency poor combustion	4 or less	Fuel injector assembly Spark plug Ignition coil assembly	Go to Rough Idling (from step 7)	A
Plural Cylinders Rough Idle is ON	One of the following is displayed: Misfire Continuous poor combustion Intermittent poor combustion Low frequency poor combustion	4 or less	Mass air flow meter Fuel injector assembly Fuel system Air fuel ratio sensor	Go to Rough Idling (from step 15)	B
"One of Rough Idle #1 to #4 is ON" or "Plural Cylinders Rough Idle is ON"	One of the following is displayed: Misfire Continuous poor combustion Intermittent poor combustion Low frequency poor combustion	5 or more	Pressure loss from valve damage, deposits jamming the valve etc.	Check compression and clean deposits in combustion chamber and intake system.	C

GO TO STEP 4

GO TO STEP 5

3.	DETERMINE CAUSE OF MALFUNCTION FOR INDIVIDUAL CYLINDER

(a) Perform troubleshooting from Rough Idling step 7 (PERFORM ACTIVE TEST USING TECHSTREAM (CHECK THE CYLINDER COMPRESSION)) and onward.

Click here

GO TO ROUGH IDLING

4.	DETERMINE CAUSE OF MALFUNCTION FOR MULTIPLE OR ALL CYLINDERS

(a) Perform troubleshooting from Rough Idling step 15 (READ VALUE USING TECHSTREAM (MAF)) and onward.

Click here

GO TO ROUGH IDLING

5.	PERFORM ACTIVE TEST USING TECHSTREAM (CHECK THE CYLINDER COMPRESSION)

(a) Warm up the engine.

(b) Turn the ignition switch off.

(d) Turn the ignition switch to ON.

(e) Turn the Techstream on.

(f) Enter the following menus: Powertrain / Engine and ECT / Active Test / Check the Cylinder Compression / Data List / Engine Speed of Cyl #1 to #4 and Av Engine Speed of All Cyl.

Powertrain > Engine and ECT > Active Test

Active Test Display
Check the Cylinder Compression

Data List Display
Engine Speed of Cyl #1
Engine Speed of Cyl #2
Engine Speed of Cyl #3
Engine Speed of Cyl #4
Av Engine Speed of All Cyl

HINT:

To display the entire Data List, press the pull down menu button next to Primary. Then select Compression.

(g) Push the snapshot button to turn the snapshot function on.

HINT:

Using the snapshot function, data can be recorded during the Active Test.

(h) While the engine is not running, press the Active Test button to change Check the Cylinder Compression to ON.

HINT:

After performing the above procedure, the Active Test will start. Fuel injection for all cylinders is prohibited and each cylinder engine speed measurement enters standby mode.

(i) Crank the engine for about 10 seconds.

HINT:

Continue to crank the engine until the values change from the default value (51199 rpm).

(j) Monitor the engine speed (Engine Speed of Cyl and Av Engine Speed of All Cyl) displayed on the Techstream.

NOTICE:

In order to protect the starter assembly, do not crank the engine continuously for 20 seconds or more.
If it is necessary to crank the engine again after Check the Cylinder Compression has been changed to ON and the engine has been cranked once, press Exit to return to the Active Test menu screen. Then change Check the Cylinder Compression to ON and crank the engine.
Make sure the battery is fully charged before performing this Active Test.

HINT:

At first, the Techstream will display extremely high cylinder engine speed values. After approximately 10 seconds of engine cranking, the engine speed measurement of each cylinder will change to the actual engine speed.
If the cylinder engine speed values (Engine Speed of Cyl #1 to #4) displayed in the Data List do not change from an extremely high value, return to the Active Test menu screen, change "Check the Cylinder Compression" to ON and crank the engine again within 1 second.

(k) Stop cranking the engine, and then change "Check the Cylinder Compression" to OFF after the engine stops.

NOTICE:

If the Active Test is changed to OFF while the engine is being cranked, the engine will start.
When performing the Active Test, DTC P1604 (Startability Malfunction) may be stored.
After performing the Active Test, make sure to check and clear DTCs.

(l) Push the snapshot button to turn the snapshot function off.

(m) Select "Stored Data" on the Techstream screen, select the recorded data and display the data as a graph.

HINT:

If the data is not displayed as a graph, the change of the values cannot be observed.

(n) Check the change in engine speed values.

HINT:

If the value of Data List item "Engine Speed of Cyl" of a cylinder is higher than other cylinders, the cylinder may be malfunctioning.
If the value of Data List item "Engine Speed of Cyl" is high for only one cylinder, compression loss is suspected.

Result

Proceed to

There is no variation in "Engine Speed of Cyl"

(All cylinders display approximately the same value for "Engine Speed of Cyl")

There is variation in "Engine Speed of Cyl"

(Only one cylinder displays a value for "Engine Speed of Cyl" that differs considerably)

CLEAN OFF ANY DEPOSITS

6.	CHECK CYLINDER COMPRESSION PRESSURE

(a) Measure the cylinder compression pressure. If the compression pressure of a cylinder is low, inspect the engine assembly and repair or replace parts as necessary.

Click here

END