Toyota 1 MZ–FE Manual page 479

INSPECTION PROCEDURE
Check for open and short in harness and connector between ECM and heated
oxygen sensor (See page IN–31).
Check for heated oxygen sensor data.
Check the output voltage of heated oxygen sensor during idling.
Replace heated oxygen sensor.
1MZ–FE ENGINE – CIRCUIT INSPECTION
Repair or replace harness or connector.
(1) Remove the fuse cover on the instrument
panel.
(2) Connect the OBD II scan tool or TOYOTA
hand–held tester to the DLC 3.
(3) Warm up engine to normal operating
temperature.
Read the heated oxygen sensor output voltage and
short–term fuel trim.
Read the values for the same bank.
Pattern
Check fuel trim system.
(1),(2)
(See page EG2–486).
Warm up the heated oxygen sensor with the engine
at 2,500 rpm for approx. 90 sec.
Use the OBD II scan tool or TOYOTA hand–held
tester read the output voltage of the heated ox–
ygen sensor during idling.
Heated oxygen sensor output voltage:
Alternates repeatedly between less than 0.4 V
and more than 0.55 V (See the adjacent table).
Perform confirmation driving pattern.
(See page EG2–477).
Heated oxygen
sensor output voltage
Lean condition
(Changes at 0.55 V or less)
Rich condition
(Changes at 0.4 V or more)
Except (1) and (2)
EG2–479
Short–term
fuel trim
Changes at
about +20%
Changes at
about –20%