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Home >> Toyota >> 2016 >> RAV4 SE, FWD >> Repair and Diagnosis >> Engine Performance >> Testing & Diagnosis >> SFI System [2AR-FE] (Diagnostic Codes) (Except Hybrid) (3 Of 7) >> SFI System >> DTC P0136-P0139, P013A; Oxygen Sensor Circuit Malfunction (Bank 1 Sensor 2) [08/2014 - 10/2015] >> Description

DTC P0136-P0139, P013A; Oxygen Sensor Circuit Malfunction (Bank 1 Sensor 2) [08/2014 - 10/2015]: Description

In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a TWC (Three-Way Catalytic Converter) is used. For the most efficient use of the TWC, the air fuel ratio must be precisely controlled so that it is always close to the stoichiometric air fuel level. For the purpose of helping the ECM to deliver accurate air fuel ratio control, a heated oxygen sensor is used.

The heated oxygen sensor is located behind the TWC, and detects the oxygen concentration in the exhaust gas. Since the sensor is integrated with the heater that heats the sensing portion, it is possible to detect the oxygen concentration even when the intake air volume is low (the exhaust gas temperature is low).

When the air fuel ratio becomes lean, the oxygen concentration in the exhaust gas is high. The heated oxygen sensor informs the ECM that the post-TWC air fuel ratio is lean (low voltage, i.e. less than 0.45 V).

Conversely, when the air fuel ratio is richer than the stoichiometric air fuel level, the oxygen concentration in the exhaust gas is low. The heated oxygen sensor informs the ECM that the post-TWC air fuel ratio is rich (high voltage, i.e. more than 0.45 V). The heated oxygen sensor has the property of changing its output voltage drastically when the air fuel ratio is close to the stoichiometric level.

The ECM uses the supplementary information from the heated oxygen sensor to determine whether the air fuel ratio after the TWC is rich or lean, and adjusts the fuel injection duration accordingly. Thus, if the heated oxygen sensor is working improperly due to internal malfunctions, the ECM is unable to compensate for deviations in the primary air fuel ratio control.

Fig 1: Identifying Oxygen Sensor Components & Air-Fuel Ratio Graph
GTY373586Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory Note
P0136 Oxygen Sensor Circuit Malfunction (Bank 1 Sensor 2) Either of the following conditions is met:
  • Abnormal voltage output:
    1. During active air fuel ratio control, heated oxygen sensor voltage does not increase to 0.69 V or higher for certain period of time (2 trip detection logic)
  • Low impedance:
    1. Sensor impedance less than 5 Ω for 30 seconds or more when ECM presumes sensor is warmed up and operating normally (2 trip detection logic)
  • Heated oxygen sensor (sensor 2) circuit
  • Heated oxygen sensor (sensor 2)
  • Air fuel ratio sensor (sensor 1)
  • Gas leak from exhaust system
  • Fuel pressure
  • Fuel injector assembly
  • PCV valve and hose
  • Intake system
 Comes on DTC stored DTC for Mexico Models
- Not apply
P0137 Oxygen Sensor Circuit Low Voltage (Bank 1 Sensor 2) Either of the following conditions is met:
  • Low voltage (open):
    1. During active air fuel ratio control, following conditions (a) and (b) met for certain period of time (2 trip detection logic)
    2. (a) Heated oxygen sensor voltage output less than 0.21 V
    3. (b) Target air fuel ratio rich
  • High impedance:
    1. Sensor impedance 15 kΩ or higher for 90 seconds or more when ECM presumes sensor to be warmed up and operating normally (2 trip detection logic)
  • Heated oxygen sensor (sensor 2) circuit
  • Heated oxygen sensor (sensor 2)
  • Air fuel ratio sensor (sensor 1)
  • Gas leak from exhaust system
 Comes on DTC stored DTC for Mexico Models
- Applies
P0138 Oxygen Sensor Circuit High Voltage (Bank 1 Sensor 2)
  • Extremely high voltage (short):
    1. Heated oxygen sensor voltage output exceeds 1.2 V for 10 seconds or more (2 trip detection logic)
  • Heated oxygen sensor (sensor 2) circuit
  • Heated oxygen sensor (sensor 2)
  • ECM
  • Air fuel ratio sensor (sensor 1)
 Comes on DTC stored DTC for Mexico Models
- Not apply
P0139 Oxygen Sensor Circuit Slow Response (Bank 1 Sensor 2) Heated oxygen sensor (sensor 2) voltage does not drop to below 0.2 V immediately after fuel cut starts (2 trip detection logic)
  • Heated oxygen sensor (sensor 2) circuit
  • Heated oxygen sensor (sensor 2)
  • Gas leak from exhaust system
 Comes on DTC stored DTC for Mexico Models
- Not apply
P013A Oxygen Sensor Slow Response - Rich to Lean Bank 1 Sensor 2 Heated oxygen sensor (sensor 2) voltage does not drop from 0.35 V to 0.2 V immediately after fuel cut starts (1 trip detection logic)
  • Heated oxygen sensor (sensor 2) circuit
  • Heated oxygen sensor (sensor 2)
  • Gas leak from exhaust system
 Comes on DTC stored DTC for Mexico Models
- Not apply
FOR MEXICO MODELS

DTC No. DTC Detection Conditions Trouble Areas
P0136 Not applicable None
P0137
  • Low voltage (open):
    1. During active air fuel ratio control, both of the following conditions are met for a certain period of time (2 trip detection logic):
    2. (a) The heated oxygen sensor voltage output is less than 0.21 V.
    3. (b) The target air fuel ratio is rich.
  • Heated oxygen sensor (sensor 2) circuit
  • Heated oxygen sensor (sensor 2)
  • Air fuel ratio sensor (sensor 1)
  • Gas leak from exhaust system
P0138 Not applicable None
P0139 Not applicable None
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