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Home >> Lexus >> 2007 >> SC 430 >> Repair and Diagnosis >> Engine Performance >> Engine Control System >> SFI System >> DTC P0133 Oxygen Sensor Circuit Slow Response (Bank 1 Sensor 1); DTC P0153 Oxygen Sensor Circuit Slow Response (Bank 2 Sensor 1) >> Description

DTC P0133 Oxygen Sensor Circuit Slow Response (Bank 1 Sensor 1); DTC P0153 Oxygen Sensor Circuit Slow Response (Bank 2 Sensor 1): Description

The heated oxygen sensor is used to monitor oxygen concentration in the exhaust gas. For optimum catalytic converter operation, the air-fuel mixture must be maintained near the ideal stoichiometric air-fuel ratio. The heated oxygen sensor output voltage changes suddenly in the vicinity of the stoichiometric air-fuel ratio. The ECM adjusts the fuel injection time so that the air-fuel ratio is nearly stoichiometric. The heated oxygen sensor generates a voltage between 0.1 and 0.9 V in response to oxygen concentration in the exhaust gas.

If the oxygen concentration in the exhaust gas increases, the air-fuel ratio is called LEAN. The heated oxygen sensor voltage drops below 0.45 V, which informs the ECM of the LEAN condition.

If oxygen is not in the exhaust gas, the air-fuel ratio is called RICH. The heated oxygen sensor voltage increases above 0.45 V, which informs the ECM of the RICH condition.

Fig 1: Oxygen Sensor Components With Output Voltage Graph
G05291353Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

The ECM provides a pulse width modulated control circuit to adjust current through the heater. The heated oxygen sensor heater circuit uses a relay on the +B side of the circuit.

Fig 2: Heated Oxygen Sensor Heater Circuit Diagram
G05291354Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
DTC DETECTION CONDITION CHART

DTC No. DTC Detection Condition Trouble Area
P0133
P0153
Slow slope condition (2 trip detection logic):
Heated oxygen sensor (sensor 1) does not switch between LEAN and RICH for 0.9 seconds
LEAN: 0.4 V or less
RICH: 0.55 V or more
Frequency condition (2 trip detection logic):
Time of heated oxygen sensor (sensor 1) frequency per one cycle is 0.9 seconds or more.
  • Open or short in heated oxygen sensor (sensor 1) circuit
  • Heated oxygen sensor (sensor 1)
  • EFI relay
  • Air induction system
  • Fuel pressure
  • Injector
  • ECM