SFI SYSTEM, Diagnostic DTC:P1604

DTC Code	DTC Name
P1604	Startability Malfunction

DESCRIPTION

This DTC is stored when the engine does not start even though the STA signal is input or when the engine takes a long time to start, and when the engine speed is low or the engine stalls just after the engine starts.

Using the GTS, 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 there is engine starting trouble due to running out of fuel.

DTC No.	DTC Detection Condition
P1604	Either conditions is met: The engine speed is below 500 rpm with the STA signal on for a certain amount of time (refer to the illustration below) (1 trip detection logic). After the engine starts (engine speed is 500 rpm or more), the engine speed drops to 200 rpm or less within approximately 2 seconds (1 trip detection logic).

DTC No.

DTC Detection Condition

P1604

Either conditions is met:

The engine speed is below 500 rpm with the STA signal on for a certain amount of time (refer to the illustration below) (1 trip detection logic).
After the engine starts (engine speed is 500 rpm or more), the engine speed drops to 200 rpm or less within approximately 2 seconds (1 trip detection logic).

Trouble Area
Ignition system	Spark plug Ignition coil assembly
Fuel system	Fuel injector assembly Fuel pump Fuel pump control circuit Fuel pressure regulator assembly 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 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
High load from another system	Air conditioning system Power steering system Electrical load signal system A/T system

CAUTION / NOTICE / HINT

Tech Tips

DTC P1604

In contrast to normal malfunction diagnosis for components, circuits and systems, DTC P1604 is used to determine the malfunctioning area from the problem symptoms and freeze frame data when the user mentions problems such as starting difficulty.

As this DTC can be stored as a result of certain user actions, even if the DTC is output, if the customer makes no mention of problems, clear the DTC without performing any troubleshooting and return the vehicle to the customer.

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.

DATA LIST / FREEZE FRAME DATA

When this Data List item "Immobiliser Communication" is OFF or "Immobiliser Fuel Cut" is ON, the engine cannot be started.

Read freeze frame data using the GTS. 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 the freeze frame data, if there are multiple items related to the cause of the malfunction, perform troubleshooting for all related items.

Try to start 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 compare it with the freeze frame data.

If the malfunction does not recur, carefully check the vehicle conditions from when the malfunction occurred using freeze frame data.

PRECAUTIONS

When performing inspections, jiggle the relevant wire harnesses and connectors in an attempt to reproduce malfunctions that do not always occur.

If the same inspection or replacement procedure appears 2 times when performing an inspection procedure, it is not necessary to repeat the procedure the second time.

PROCEDURE

CHECK ANY OTHER DTCS OUTPUT

Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.
Enter the following menus: Powertrain / Engine / Trouble Codes.

Read the DTCs.

Result

Result	Proceed to
DTC P1604 is output	A
DTC P1604 and other DTCs are output	B

Tech Tips

If any DTCs other than P1604 are 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 Click here

READ FREEZE FRAME DATA (IMMOBILISER COMMUNICATION AND IMMOBILISER FUEL CUT)

Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.

Using the GTS, confirm the vehicle conditions recorded in the freeze frame data which were present when the DTC was stored Click here.

Data List Item	GTS Display
Immobiliser Communication	ON
Immobiliser Fuel Cut	OFF

Tech Tips

If the engine is started immediately after reconnecting the battery terminal, the engine may stall immediately after it starts due to the intercommunication process between each ECU. For this reason, when starting the engine after reconnecting the battery terminal, first turn the engine switch on (IG) and then wait several seconds for the communication process to complete before starting the engine.
When this operation causes DTC P1604 to be stored, this is due to normal operation of the immobiliser system and does not indicate a malfunction, so clear the DTC and return the vehicle to the customer.

CHECK IMMOBILISER SYSTEM Click here

READ FREEZE FRAME DATA (ISC LEARNING VALUE)

Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.

Using the GTS, confirm the vehicle conditions recorded in the freeze frame data which were present when the DTC was stored Click here.

Result
Freeze Frame Data Item	Result	Suspected Area	Action	Proceed to
ISC Learning Value	Less than 8.5 L/s	-	Go to the next step	A
ISC Learning Value	8.5 L/s or higher	Throttle body with motor assembly	Go to Engine Difficult to Start (from step 15)	B

GO TO ENGINE DIFFICULT TO START Click here

READ FREEZE FRAME DATA (ENGINE SPEED)

Connect the GTS to the DLC3.
Turn the engine switch on (IG).
Turn the GTS on.

Using the GTS, confirm the vehicle conditions recorded in the freeze frame data which were present when the DTC was stored Click here.

Result

Freeze Frame Data Item	Result	Suspected Area	Action	Proceed to
Engine Speed	All 5 sets of freeze frame data are 0 rpm (engine did not crank or engine speed was not detected properly)	Starter signal circuit Crankshaft position sensor system Battery fully depleted	Go to Engine Difficult to Start (from step 5)	A
	100 to 500 rpm (engine cranked but initial combustion did not occur or was delayed)	Fuel pump Leaking fuel injector assembly Spark plug Ignition coil assembly	Go to the next step	B
	500 rpm or higher (engine speed dropped immediately after initial combustion) (Low Rev for Eng Start is ON)	Spark plug Ignition coil assembly	Go to the next step	B

GO TO ENGINE DIFFICULT TO START Click here

INTERVIEW THE CUSTOMER

Interview the customer for details about the conditions when the malfunction occurred.

Tech Tips

If the engine is difficult to start only when the vehicle has been left as is for a long time, a leaking fuel injector assembly is suspected.

Result

Result	Suspected Area	Action	Proceed to
Engine is difficult to start only when the vehicle has been left as is for a long time (1 hour or more)	Leaking fuel injector assembly	Go to Engine Difficult to Start (from step 4)	A
Other than above	Fuel pump Spark plug Ignition coil assembly	Go to the next step	B

GO TO ENGINE DIFFICULT TO START Click here

INTERVIEW THE CUSTOMER

Interview the customer for details about the conditions when the malfunction occurred.

Tech Tips

If the vehicle is mostly driven for short distances, deposits may have accumulated on the spark plugs, causing starting difficulty.

Result

Result	Suspected Area	Action	Proceed to
Mostly driven short distances	Spark plug Ignition coil assembly	Go to Engine Difficult to Start (from step 13)	NEXT
Not mostly driven short distances	Fuel pump Spark plug Ignition coil assembly	Go to Engine Difficult to Start (from step 9)	NEXT

GO TO ENGINE DIFFICULT TO START Click here