Toyota Celica 2005 Repair Manual page 611

DI−412
HINT:
Sensor 1 is the sensor closer to the engine body.
S
The output voltage of the heated oxygen sensor and the short−term fuel trim value can be read using
S
the OBD II scan tool or the hand−held tester.
MONITOR DESCRIPTION
Rich
0.50
0.45
0.40
Lean
The ECM uses the heated oxygen sensor information to regulate the air−fuel ratio near to the stoichiometric
air−fuel ratio. The sensor detects oxygen levels in the exhaust gas and sends this signal to the ECM. This
maximizes the catalytic converter's ability to purify the exhaust gas.
The heated oxygen sensor element consists of the platinum coated zirconia and heating element. The inner
surface of sensor element is exposed to the outside air, and the outer surface of sensor element is exposed
to the exhaust gas. The sensor generates between 0 V and 1 V of the voltage output in response to the oxy-
gen concentration in the exhaust gas. The sensor's output voltage varies suddenly in the vicinity of the stoi-
chiometric air−fuel ratio.
Under a normal condition, the output voltage from the heated oxygen sensor alternates between RICH and
LEAN sides periodically. When it is 0.4 V or less, the air−fuel ratio is judged as LEAN.
If the heated oxygen sensor outputs RICH signal (or LEAN signal) constantly, or if the heated oxygen sensor
cannot output enough voltage to reach the minimum specification, the ECM interprets this as a malfunction
in the heated oxygen sensor and sets a DTC.
MONITOR STRATEGY
Related DTCs
Required sensors/components
Frequency of operation
Duration
MIL operation
Sequence of operation
2005 CELICA (RM1131U)
DIAGNOSTICS −
PASS
Pass / Fail definition of voltage malfunction
P0130
P2195
P2196
Main sensors/components
Related sensors/components
Once per driving cycle
20 to 36 sec. x (3 time)
2 driving cycles
None
610
ENGINE (2ZZ−GE)
FAIL
FAIL
FAIL
Front heated oxygen sensor voltage is constant
Front heated oxygen sensor voltage is constant
at lean side
Front heated oxygen sensor voltage is constant
at rich side
Front heated oxygen senor
Crank position sensor, Vehicle speed sensor
Time
A20806