Brand:

Toyota

Model Name:

4Runner GRN210 215 UZN210 215

Manual:

Repair Manual

Section:

1Gr-Fe Engine Control System

Title:

Sfi System

  1. Description

  2. Monitor description

  3. Monitor strategy

  4. Typical enabling conditions

  5. Typical malfunction thresholds

  6. Component operating range

  7. Monitor result

  8. Wiring diagram

  9. Inspection procedure

  10. Inspect air fuel ratio sensor (heater resistance)

  11. Inspect air fuel ratio sensor relay

  12. Inspect ecm (ha1a or ha2a voltage)

  13. Check harness and connector (a/f sensor - ecm, a/f sensor - a/f sensor heater 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)

HINT:
  1. Although the DTC titles say the 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.

DESCRIPTION

Refer to DTC P2195 (Click here).
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 ignition 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.

Open in A/F sensor heater circuit 4Runner


DTC No.
DTC Detection Conditions
Trouble Areas
P0031
P0051
Air-Fuel Ratio (A/F) sensor heater current less than 0.8 A (1 trip detection logic)
  1. Open in A/F sensor heater circuit
  2. A/F sensor heater
  3. A/F sensor heater relay
  4. ECM
P0032
P0052
Air-Fuel Ratio (A/F) sensor heater current more than 10 A (1 trip detection logic)
  1. Short in A/F sensor heater circuit
  2. A/F sensor heater
  3. A/F sensor heater 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 closest sensor to the engine assembly.
  4. Sensor 2 refers to the furthest sensor away from the engine assembly.

MONITOR DESCRIPTION

The ECM uses information from the Air-Fuel Ratio (A/F) sensor to regulate the air-fuel ratio and keep it close to the stoichiometric level. This maximizes the ability of the Three-Way Catalytic Converter (TWC) to purify the exhaust gas.
The A/F sensor detects oxygen levels in the exhaust gas and transmits the information to the ECM. The inner surface of the sensor element is exposed to the outside air. The outer surface of the sensor element is exposed to the exhaust gas. The sensor element is made of platinum coated zirconia and includes an integrated heating element.
The zirconia element generates small voltage when there is a large difference in the oxygen concentrations between the exhaust gas and outside air. The platinum coating amplifies this voltage generation.
The A/F sensor is more efficient when heated. When the exhaust gas temperature is low, the sensor cannot generate useful voltage signals without supplementary heating. The ECM regulates the supplementary heating using a duty-cycle approach to adjust the average current in the sensor heater element. If the heater current is outside the normal range, the signal transmitted by the A/F sensor will be inaccurate, as a result, the ECM will be unable to regulate air-fuel ratio properly.
When the current in the A/F sensor heater is outside the normal operating range, the ECM interprets this as a malfunction in the sensor heater and sets a DTC.
Example:
  1. The ECM sets DTC P0032 or P0052 when the current in the A/F sensor heater is more than 10 A. Conversely, when the heater current is less than 0.8 A, DTC P0031 or P0051 is set.

MONITOR STRATEGY


Related DTCs
P0031: A/F sensor heater (Bank 1) range check (Low current)
P0032: A/F sensor heater (Bank 1) range check (High current)
P0051: A/F sensor heater (Bank 2) range check (Low current)
P0052: A/F sensor heater (Bank 2) range check (High current)
Required sensors / components (Main)
A/F sensor heater
Required sensors / components (Related)
-
Frequency of operation
Continuous
Duration
10 seconds
MIL operation
Immediate
Sequence operation
None

TYPICAL ENABLING CONDITIONS


All:
The monitor will run whenever these DTCs are not present
None

P0031 and P0051:
Battery voltage
10.5 V or more
A/F sensor heater duty ratio
50% or more
Time after engine start
10 seconds or more

P0032 and P0052:
Time after engine start
10 seconds or more

TYPICAL MALFUNCTION THRESHOLDS


P0031 and P0051:
A/F sensor heater current
Less than 0.8 A

P0032 and P0052:
A/F sensor heater current
More than 10 A

COMPONENT OPERATING RANGE


A/F sensor heater current
1.8 to 3.4 A at 20°C (68°F)

MONITOR RESULT

Refer to Checking Monitor Status for detailed information (Click here).
The test value and test limit information are described as shown in the following table. Check the monitor result and test values after performing the monitor drive pattern (Click here).
  1. TID (Test Identification Data) is assigned to each emissions-related component.
  2. TLT (Test Limit Type):
    If TLT is 0, the component is malfunctioning when the test value is higher than the test limit.
    If TLT is 1, the component is malfunctioning when the test value is lower than the test limit.
  3. CID (Component Identification Data) is assigned to each test value.
  4. Unit Conversion is used to calculate the test value indicated on generic OBD II scan tools.

TID $07: A/F sensor heater
TLT
CID
Unit Conversion
Description of Test Data
Description of Test Limit
1
$01
Multiply by 0.00017 (A)
Maximum heater current (Bank 1)
Malfunction criterion for A/F sensor heater
1
$10
Multiply by 0.00017 (A)
Maximum heater current (Bank 2)
Malfunction criterion for A/F sensor heater

WIRING DIAGRAM

Refer to DTC P2195 (Click here).

INSPECTION PROCEDURE

HINT:
Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air/fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.
1.INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)
  1. Disconnect the A12 or A13 A/F sensor connector. 4Runner

  2. Disconnect the A12 or A13 A/F sensor connector.

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

    Standard resistance:
    Tester Connections
    		Specified Conditions
    HT (1) - +B (2)
    		1.8 to 3.4 Ω at 20°C (68°F)
    HT (1) - AF- (4)
    		10 kΩ or higher

  1. Reconnect the A/F sensor connector.



NGnext
REPLACE AIR FUEL RATIO SENSOR
OK
next down

2.INSPECT AIR FUEL RATIO SENSOR RELAY
  1. Remove the A/F sensor heater relay from the engine room R/B. 4Runner

  2. Remove the A/F sensor heater relay from the engine room R/B.

  1. Measure the A/F sensor heater relay resistance.

    Standard resistance:
    Tester Connections
    		Specified Conditions
    3 - 5
    		10 kΩ or higher
    3 - 5
    		Below 1 Ω
    (when battery voltage applied to terminals 1 and 2)

  1. Reinstall the A/F sensor heater relay.



NGnext
REPLACE AIR FUEL RATIO SENSOR RELAY
OK
next down

3.INSPECT ECM (HA1A OR HA2A VOLTAGE)
  1. Turn the ignition switch on (IG). 4Runner

  2. Turn the ignition switch on (IG).

  1. Measure the voltage between the terminals of the E5 ECM connector.

    Standard voltage:
    Tester Connections
    		Specified Conditions
    HA1A (E5-2) - E04 (E5-7)
    		9 to 14 V
    HA2A (E5-1) - E05 (E5-6)
    		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.


OKnext
REPLACE ECM
NG
next down

4.CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM, A/F SENSOR - A/F SENSOR HEATER RELAY)
  1. Check the harness and the connector between the ECM and the A/F sensor.Disconnect the A12 or A13 A/F sensor connector.Disconnect the E5 ECM connector.Measure the resistance.Standard resistance (Check for open):Tester ConnectionsSpecified ConditionsHT (A12-1) - HA1A (E5-2)Below 1 ΩHT (A13-1) - HA2A (E5-1)Below 1 ΩStandard resistance (Check for short):Tester ConnectionsSpecified ConditionsHT (A12-1) or HA1A (E5-2) - Body ground10 kΩ or higherHT (A13-1) or HA2A (E5-1) - Body ground10 kΩ or higher 4Runner

  2. Check the harness and the connector between the ECM and the A/F sensor.

    1. Disconnect the A12 or A13 A/F sensor connector.

    2. Disconnect the E5 ECM connector.

    3. Measure the resistance.

      Standard resistance (Check for open):
      Tester Connections
      		Specified Conditions
      HT (A12-1) - HA1A (E5-2)
      		Below 1 Ω
      HT (A13-1) - HA2A (E5-1)
      		Below 1 Ω
      Standard resistance (Check for short):
      Tester Connections
      		Specified Conditions
      HT (A12-1) or HA1A (E5-2) - Body ground
      		10 kΩ or higher
      HT (A13-1) or HA2A (E5-1) - Body ground
      		10 kΩ or higher

  1. Check the harness and the connector between the A/F sensor and engine room junction block (A/F sensor heater relay).

    1. Remove the engine room junction block.

    2. Measure the resistance.

      Standard resistance (Check for open):
      Tester Connections
      		Specified Conditions
      +B (A12-2) -A/F sensor heater relay (3)
      		Below 1 Ω
      +B (A13-2) -A/F sensor heater relay (3)
      		Below 1 Ω
      Standard resistance (Check for short):
      Tester Connections
      		Specified Conditions
      +B (A12-2) or A/F sensor heater relay (3) - Body ground
      		10 kΩ or higher
      +B (A13-2) or A/F sensor heater relay (3) - Body ground
      		10 kΩ or higher

    3. Reconnect the A/F sensor connector.

    4. Reconnect the ECM connector.

    5. Reinstall the A/F sensor heater relay.



NGnext
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK
next down
REPLACE ECM