DTC P0133: Heated Oxygen Sensor Circuit Slow Response (sensor 1)

CIRCUIT OPERATION
• A voltage corresponding to the oxygen concentration in the exhaust gas is sent to the ECM (terminal No. 76) <M/T> or PCM (terminal No. 71) <A/T> from the output terminal (terminal No. 4) of the heated oxygen sensor (front).
• Terminal No. 2 of the heated oxygen sensor (front) is grounded with ECM (terminal No. 92) <M/T> or PCM (terminal No. 57) <A/T>.
TECHNICAL DESCRIPTION
• The heated oxygen sensor (front) detects the concentration of oxygen in the exhaust gas; it converts those data to voltage, and inputs the resulting signals to the ECM <M/T> or PCM <A/T>.
• When the heated oxygen sensor (front) begins to deteriorate, the heated oxygen sensor signal response becomes poor.
• The ECM <M/T> or PCM <A/T> forcibly varies the air/fuel mixture to make it leaner and richer, and checks the response speed of the heated oxygen sensor (front). In addition, the ECM <M/T> or PCM <A/T> also checks for an open circuit in the heated oxygen sensor (front) output line.
DESCRIPTIONS OF MONITOR METHODS
• If the inversion frequency is low while monitoring the lean/rich inversion frequency of the heated oxygen sensor (front), the heated oxygen sensor (front) is determined to have deteriorated.
MONITOR EXECUTION
Continuous
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
• Heated oxygen sensor (front) heater monitor
• Misfire monitor
• Fuel system monitor

Sensor (The sensor below is determined to be normal)
• Volume airflow sensor
• Intake air temperature sensor
• Engine coolant temperature sensor
• Throttle position sensor
• Barometric pressure sensor
DTC SET CONDITIONS Logic Flow Chart


Check Conditions
Engine coolant temperature is higher than 50°C (122°F).
Engine speed is at between 1,200 and 3,000 r/min.
Volumetric efficiency is at between 20 and 60 percent.
Under the closed loop air/fuel control.
Short-term fuel trim is at between -25 percent and +25 percent.
The throttle valve is open.
More than 2 seconds have elapsed after the above mentioned conditions have been met.
The ECM <M/T> or PCM <A/T> monitors for this condition for 5 cycles of 10 seconds each during the drive cycle.

Judgment Criterion
• The heated oxygen sensor (front) sends "lean" and "rich" signals alternately 10 times or less for 10 seconds.
NOTE: If the sensor switching frequency is lower than the Judgment Criteria due to the MUT-III OBD-II test Mode - H02S Test Results, it is assumed that the heated oxygen sensor has deteriorated. If it is higher, it is assumed that the harness is damaged or has a short circuit.
If the heated oxygen sensor signal voltage has not changed even once (lean/rich) after the DTC was erased, the sensor switch time will display as 0 seconds.
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 1 .
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are: )
• Heated oxygen sensor (front) deteriorated.
• ECM failed. <M/T>
• PCM failed. <A/T>