Diagnostic trouble code P0031 P0032 P0051 P0052 4GR-FSE Engine

Description

Wiring diagram

Inspection procedure

INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

INSPECT A/F HTR RELAY

INSPECT ECM

CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM, A/F SENSOR - A/F HTR RELAY)

DTC P0031 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 1 Sensor 1)

DTC P0032 Oxygen (A/F) Sensor Heater Control Circuit High (Bank 1 Sensor 1)

DTC P0051 Oxygen (A/F) Sensor Heater Control Circuit Low (Bank 2 Sensor 1)

DTC P0052 Oxygen (A/F) Sensor Heater Control Circuit High (Bank 2 Sensor 1)

Description

HINT:

  1. Although the DTC titles say oxygen sensor, these DTCs relate to the Air-Fuel Ratio (A/F) sensor.
  2. Sensor 1 refers to the sensor mounted in front of the Three-Way Catalytic Converter (TWC) and located near the engine assembly.

The A/F sensor generates voltage* that corresponds to the actual air-fuel ratio. This sensor voltage is used to provide the ECM with feedback so that it can control the air-fuel ratio. The ECM determines the deviation from the stoichiometric air-fuel ratio level, and regulates the fuel injection time. If the A/F sensor malfunctions, the ECM is unable to control the air-fuel ratio accurately. The A/F sensor is the planar type and is integrated with the heater, which heats the solid electrolyte (zirconia element). This heater is controlled by the ECM. When the intake air volume is low (the exhaust gas temperature is low), a current flows into the heater to heat the sensor, in order to facilitate accurate oxygen concentration detection. In addition, the sensor and heater portions are narrower than the conventional type. The heat generated by the heater is conducted to the solid electrolyte though the alumina, therefore the sensor activation is accelerated. 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 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 level. *: Value changes inside the ECM. Since the A/F sensor is the current output element, a current is converted to a voltage inside the ECM. Any measurements taken at the A/F sensor or ECM connectors will show a constant voltage.

Diagnostic trouble code P0031 P0032 P0051 P0052 4GR-FSE Engine.

HINT:

  1. When any of these DTCs are set, the ECM enters fail-safe mode. The ECM turns off the A/F sensor heater in fail-safe mode. Fail-safe mode continues until the engine switch is turned off.
  2. The ECM provides a pulse width modulated control circuit to adjust the current through the heater. The A/F sensor heater circuit uses a relay on the B+ side of the circuit.

    Diagnostic trouble code P0031 P0032 P0051 P0052 4GR-FSE Engine. Description

DTC No. DTC Detection Condition Trouble Area
P0031
P0051		 Air-Fuel Ratio (A/F) sensor heater (bank 1 sensor 1) current less than 0.8 A (1 trip detection logic)
  1. Open in A/F sensor heater (bank 1 sensor 1) circuit
  2. A/F sensor heater (bank 1 sensor 1)
  3. A/F HTR relay
  4. ECM
P0032
P0052		 Air-Fuel Ratio (A/F) sensor heater (bank 2 sensor 1) current more than 10 A (1 trip detection logic)
  1. Short in A/F sensor heater (bank 2 sensor 1) circuit
  2. A/F sensor heater (bank 2 sensor 1)
  3. A/F HTR relay
  4. ECM

HINT:

  1. Bank 1 refers to the bank that includes cylinder No. 1.
  2. Bank 2 refers to the bank that does not include cylinder No. 1.
  3. Sensor 1 refers to the sensor closest to the engine assembly.
  4. Sensor 2 refers to the sensor farthest away from the engine assembly.

Wiring diagram

Diagnostic trouble code P0031 P0032 P0051 P0052 4GR-FSE Engine. Wiring diagram

Inspection procedure

HINT:

Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred .

 

1.INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

Diagnostic trouble code P0031 P0032 P0051 P0052 4GR-FSE Engine. Disconnect the E42 or E38 A/F sensor connector.

  1. Disconnect the E42 or E38 A/F sensor connector.

  1. Measure the resistance of the A/F sensor connector.

    Standard resistance (Bank 1 sensor 1):

    Tester Connection Condition Specified Condition
    HA1A (1) - +B (2) 20°C (68°F) 1.8 to 3.4 ?
    HA1A (1) - A1A- (4) - 10 k? or higher

    Standard resistance (Bank 2 sensor 1):

    Tester Connection Condition Specified Condition
    HA2A (1) - +B (2) 20°C (68°F) 1.8 to 3.4 ?
    HA2A (1) - A2A- (4) - 10 k? or higher

  1. Reconnect the A/F sensor connector.

  NG  
REPLACE AIR FUEL RATIO SENSOR
 
OK  
   

2.INSPECT A/F HTR RELAY

Diagnostic trouble code P0031 P0032 P0051 P0052 4GR-FSE Engine. Remove the A/F HTR relay from the engine room J/B and R/B No. 2.

  1. Remove the A/F HTR relay from the engine room J/B and R/B No. 2.

  1. Measure the resistance of the A/F HTR relay.

    Standard resistance:

    Tester Connection Specified Condition
    3 - 5 10 k? or higher
    3 - 5 Below 1 ?
    (when battery voltage applied to terminals 1 and 2)

  1. Reinstall the A/F HTR relay.

  NG  
REPLACE A/F HTR RELAY
 
OK  
   

3.INSPECT ECM

Diagnostic trouble code P0031 P0032 P0051 P0052 4GR-FSE Engine. Turn the engine switch on (IG).

  1. Turn the engine switch on (IG).

  1. Measure the voltage of the E6 ECM connector.

    Standard voltage:

    Tester Connection Specified Condition
    HA1A (E6-6) - E04 (E6-5) 9 to 14 V
    HA2A (E6-4) - E05 (E6-3) 9 to 14 V

    HINT:

    1. The HA1A means the A/F sensor bank 1 sensor 1.
    2. The HA2A means the A/F sensor bank 2 sensor 1.
  OK  
REPLACE ECM
 
NG  
   

4.CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM, A/F SENSOR - A/F HTR RELAY)

Diagnostic trouble code P0031 P0032 P0051 P0052 4GR-FSE Engine. Check the wire harness and the connector between the ECM and the A/F sensor ECM and body ground.

  1. Check the wire harness and the connector between the ECM and the A/F sensor ECM and body ground.

    1. Disconnect the E42 or E38 A/F sensor connector.

    2. Disconnect the E6 ECM connector.

    3. Measure the resistance of the wire harness side connector.

      Standard resistance (Check for open):

      Tester Connection Specified Condition
      HA1A (E42-1) - HA1A (E6-6) Below 1 ?
      HA2A (E38-1) - HA2A (E6-4) Below 1 ?
      E04 (E6-5) - Body ground Below 1 ?
      E05 (E6-3) - Body ground Below 1 ?

      Standard resistance (Check for short):

      Tester Connection Specified Condition
      HA1A (E42-1) or HA1A (E6-6) - Body ground 10 k? or higher
      HA2A (E38-1) or HA2A (E6-4) - Body ground 10 k? or higher

    4. Reconnect the A/F sensor connector.

    5. Reconnect the ECM connector.

  1. Check the wire harness and the connector between the A/F sensor and A/F HTR relay.

    1. Disconnect the E42 or E38 A/F sensor connector.

    2. Remove the A/F HTR relay from the engine room J/B and R/B No. 2.

    3. Measure the resistance of the wire harness side connector.

      Standard resistance (Check for open):

      Tester Connection Specified Condition
      +B (E42-2) - A/F HTR relay (3) Below 1 ?
      +B (E38-2) - A/F HTR relay (3) Below 1 ?

      Standard resistance (Check for short):

      Tester Connection Specified Condition
      +B (E42-2) or A/F HTR relay (3) - Body ground 10 k? or higher
      +B (E38-2) or A/F HTR relay (3) - Body ground 10 k? or higher

    4. Reconnect the A/F sensor connector.

    5. Reinstall the A/F HTR relay.

  NG  
REPAIR OR REPLACE HARNESS OR CONNECTOR
 
OK  
   
REPLACE ECM