Typical Malfunction Thresholds

WARNING: This page is about a different car, the 2006 Lexus IS 350. However, it is still accessible from the selected car via links, so may be relevant.

TYPICAL MALFUNCTION THRESHOLDS

Duration that both following conditions 1 and 2 are met:	5 seconds or more
1. Simulated ECT	75°C (167°F) or more
2. ECT sensor output	Below 75°C (167°F)

HINT:

Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air/fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction (See FREEZE FRAME DATA ).

CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC P0128)

Connect the intelligent tester to the DLC3.
Turn the Engine switch on (IG).
Turn the tester on.
Enter the following menus: DIAGNOSIS / ENHANCED II / DTC INFO / CURRENT CODES.

Read the DTC.

Result

RESULT REFERENCE

Display (DTC Output)	Proceed to
P0128	A
P0128 and other	DTCs B

HINT:

If any DTC other than P0128 are output, troubleshoot those DTCs first.

B : GO TO DTC CHART

A : GO TO NEXT STEP

CHECK COOLING SYSTEM
1. Check for defects in the cooling system that might cause the system to be too cold, such as abnormal radiator fan operation or any modifications.
NG : REPAIR OR REPLACE COOLING SYSTEM

OK : GO TO NEXT STEP
INSPECT THERMOSTAT
1. Remove the thermostat (See REMOVAL ).
2. Check the valve opening temperature of the thermostat.
  Standard: 80 to 84°C (176 to 183°F)
  
  HINT:
  
  In addition to the above check, confirm that the valve is completely closed when the temperature is below the standard.
3. Reinstall the thermostat (See INSTALLATION ).
NG : REPLACE THERMOSTAT

OK : REPLACE ECM