Toyota Celica 2005 Repair Manual page 630

DTC P0134
CIRCUIT DESCRIPTION
Refer to DTC P0130 on page DI−411.
DTC No.
After engine is warmed up, heated oxygen sensor (bank 1
sensor 1) output does not indicate RICH (greater than 0.45 V)
even once when conditions (a), (b), (c), (d) and (e) continue for
more than 65 seconds (1 trip detection logic) :
(a) Engine speed: 1,400 rpm or more
P0134
(b) Vehicle speed: 24.8 mph (40 km/h) or more
(c) Throttle valve is not fully closed
(d) 180 seconds or more after starting engine
(e) Engine coolant temperature is more than 40 _C (104 _F)
HINT:
Sensor 1 is the sensor closer to the engine body.
S
After confirming DTC P0134, check the output voltage of the heated oxygen sensor (bank 1 sensor
S
1) in the "DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL" using the hand−held tester or the OBD
II scan tool. If the output voltage of the heated oxygen sensor is always less than 0.1 V, the sensor
circuit may be open or shorted.
MONITOR DESCRIPTION
The ECM uses the heated oxygen sensor to optimize the air−fuel mixture in closed−loop fuel control. This
control helps decrease exhaust emissions by providing the catalyst with a nearly stoichiometric mixture.
The sensor detects the oxygen level in the exhaust gas and the ECM uses this data to control the air−fuel
ratio. The sensor output voltage ranges from 0 V to 1 V. If the signal voltage is less than 0.4 V, the air−fuel
ratio is LEAN. If the signal voltage is more than 0.5 V, the air−fuel ratio is RICH. If the sensor does not indicate
RICH even once despite the conditions for the closed−loop fuel control being met and a specified time period
has passed, the ECM will conclude that the closed−loop fuel control is malfunctioning. The ECM will illumi-
nate the MIL and a DTC is set.
MONITOR STRATEGY
Related DTCs
Required sensors/components
Frequency of operation
Duration
MIL operation
Sequence of operation
2005 CELICA (RM1131U)
DIAGNOSTICS
Oxygen Sensor Circuit No Activity Detected
(Bank 1 Sensor 1)
DTC Detecting Condition
Main sensors/components
Related sensors/components
Once per driving cycle
65 sec.
1 driving cycle
None
− ENGINE (2ZZ−GE)
S Open or short in heated oxygen sensor (bank 1 sensor 1)
circuit
S Heated oxygen sensor (bank 1 sensor 1)
S Heated oxygen sensor heater (bank 1 sensor 1)
S EFI relay
S Air induction system
S Fuel pressure
S PCV hose connection
S PCV valve and hose
S Injector
S Gas leakage in exhaust system
S PCV piping
S ECM
P0134
629
Trouble Area
Excessive time to enter closed−loop
Front heated oxygen sensor
Crankshaft position sensor, Engine coolant tem-
perature sensor, Vehicle speed sensor
DI−431
DIC7C−02