Toyota Celica 2005 Repair Manual page 621

DI−422
DTC P0133
CIRCUIT DESCRIPTION
Refer to DTC P0130 on page DI−411.
DTC No.
Response time of heated oxygen sensor's output voltage in
one RICH−LEAN cycle is a specific time or more during ve-
P0133
hicle running.
(2 trip detection logic)
HINT:
Sensor 1 is the sensor closest to the engine assembly.
MONITOR DESCRIPTION
The ECM uses the heated oxygen sensor information to regulate the air−fuel ratio close to a stoichiometric
ratio. This maximizes the catalytic converter's ability to purify the exhaust gas. The sensor detects oxygen
levels in the exhaust gas and sends this signal to the ECM.
The inner surface of the sensor element is exposed to outside air. The outer surface of the sensor element
is exposed to exhaust gas. The sensor element is made of platinum coated zirconia and includes an inte-
grated heating element. The heated oxygen sensor has the characteristic, whereby its output voltage
changes suddenly in the vicinity of the stoichiometric air−fuel ratio. The heated oxygen sensor generates
waveforms of a voltage between 0 V and 1 V in response to the oxygen concentration in exhaust gas. When
the output voltage of the heated oxygen sensor is 0.55 V or more, the ECM judges that the air−fuel ratio is
RICH. When it is 0.40 V or less, the ECM judges that the air−fuel ratio is LEAN.
The ECM monitors the response feature of the heated oxygen sensor. If the response time of the sensor
output status change from RICH to LEAN or vice versa becomes longer, the ECM interprets this as a mal-
function in the heated oxygen sensor and sets a DTC.
2005 CELICA (RM1131U)
DIAGNOSTICS
Oxygen Sensor Circuit Slow Response
(Bank 1 Sensor 1)
DTC Detecting Condition
− ENGINE (2ZZ−GE)
S Open or short in heated oxygen sensor circuit (bank 1 sensor
1)
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 Injector
S ECM
620
Trouble Area
DIC7B−02