DTC 054 High Setting of Flame Cutout

DTC 056 Low Setting of Flame Cutout

DTC No.	DTC Detection Condition	Trouble Area
054	Combustion ends abnormally (High output operation).	Exhaust air duct Intake air duct Fuel pump filter Heater fuel pump Combustion heater assembly
056	Combustion ends abnormally (Low output operation).

Before performing the following inspections, attempt to restart the combustion heater assembly. If the combustion heater assembly is successfully started, confirm that neither DTC 054 nor DTC 056 is output. If neither DTC 054 nor 056 is output, finish troubleshooting because it can be concluded that the system has returned to normal operation.

1.INSPECT INTAKE AIR DUCT

Inspect the intake air duct.

Result:
Result Proceed to
There is no problem with the intake air duct. A
The intake air duct is clogged, or other problems are found. B

B

CLEAN OR REPLACE INTAKE AIR DUCT

A

2.INSPECT EXHAUST AIR DUCT

Inspect the exhaust air duct.

Result:
Result Proceed to
There is no problem with the exhaust air duct. A
The exhaust air duct is clogged, or other problems are found. B

B

CLEAN OR REPLACE EXHAUST AIR DUCT

A

3.INSPECT HEATER FUEL PUMP

Measure the resistance according to the value(s) in the table below.

Inspect heater fuel pump operation.

Connect the positive (+) lead from the battery to terminal 2 and the negative (-) lead to terminal 1, and check the pressure of the hose by hand.

This inspection must be done quickly (within 10 seconds) to prevent damage to the heater fuel pump.

NG

REPLACE HEATER FUEL PUMP

OK

4.REPLACE FUEL PUMP FILTER

Replace the fuel filter with a normal one and check that the condition returns to normal.

OK

END

NG

REPLACE COMBUSTION HEATER ASSEMBLY

LEXUS IS250, IS220d / GSE20 ALE20

Result	Proceed to
There is no problem with the intake air duct.	A
The intake air duct is clogged, or other problems are found.	B

Result	Proceed to
There is no problem with the exhaust air duct.	A
The exhaust air duct is clogged, or other problems are found.	B

Tester connection	Condition	Specified condition
Q55-2 - Q55-1	Always	9 to 12 Ω