DTC    P2238    Oxygen (A/F) Sensor Pumping Current Circuit Low (Bank 1 Sensor 1)

DTC    P2239    Oxygen (A/F) Sensor Pumping Current Circuit High (Bank 1 Sensor 1)

DTC    P2252    Oxygen (A/F) Sensor Reference Ground Circuit Low (Bank 1 Sensor 1)

DTC    P2253    Oxygen (A/F) Sensor Reference Ground Circuit High (Bank 1 Sensor 1)

for Preparation Click here


DESCRIPTION

HINT:
These DTCs are related to the A/F sensor.

Refer to DTC P2195 (Click here).

DTC No.
DTC Detection Condition
Trouble Area
P2238
  1. Condition (a) or (b) continues for 5.0 seconds or more:
    (a) AF+ is 0.5 V or less
    (b) (AF+) - (AF-) is 0.1 V or less
  1. A/F sensor admittance: Less than 0.022 1/Ω
  1. Open or short in A/F sensor (sensor 1) circuit
  2. A/F sensor (sensor 1)
  3. A/F sensor heater
  4. A/F relay
  5. A/F sensor heater and relay circuits
  6. ECM
P2239
  1. Condition (a) or (b) continues for 5.0 seconds or more:
    (a) AF+ is more than 4.5 V
    (b) (AF+) - (AF-) is more than 0.8 V
  1. Open or short in A/F sensor (sensor 1) circuit
  2. A/F sensor (sensor 1)
  3. A/F sensor heater
  4. A/F relay
  5. A/F sensor heater and relay circuits
  6. ECM
P2252
AF- is 0.5 V or less for 5.0 seconds or more
  1. Open or short in A/F sensor (sensor 1) circuit
  2. A/F sensor (sensor 1)
  3. A/F sensor heater
  4. A/F relay
  5. A/F sensor heater and relay circuits
  6. ECM
P2253
AF- is more than 4.5 V for 5.0 seconds or more
  1. Open or short in A/F sensor (sensor 1) circuit
  2. A/F sensor (sensor 1)
  3. A/F sensor heater
  4. A/F relay
  5. A/F sensor heater and relay circuits
  6. ECM

WIRING DIAGRAM

Refer to DTC P2195 (Click here).

INSPECTION PROCEDURE

HINT:
Intelligent tester only:
Malfunctioning areas can be found by performing the Active Test / A/F Control operation. The A/F Control operation can determine if the A/F sensor, heated oxygen sensor or other potential trouble areas are malfunctioning or not.

(a) Perform Active Test using the intelligent tester.

HINT:
The A/F Control operation lowers the injection volume by 12.5% or increases the injection volume by 25%.
  1. Connect the intelligent tester to the DLC3.
  2. Start the engine and turn the intelligent tester ON.
  3. Warm up the engine by running the engine at 2,500 rpm for approximately 90 seconds.
  4. On the intelligent tester, select the following menu items: Powertrain / Engine and ECT / Active Test /A/F control.
  5. Select the following monitor items: AFS B1S1 and O2S B1S2.
  6. Perform the A/F Control operation with the engine in an idling condition (press the right or left button).

HINT:
  1. The A/F control operation lowers the fuel injection volume by 12.5% or increases the injection volume by 25%.
  1. Each sensor reacts in accordance with increases and decreases in the fuel injection volume.


Standard:

Tester Display
(Sensor)
Injection Volume
Status
Voltage
AFS B1S1 or AFS B1 S1
(A/F)
+25%
Rich
Less than 3.0 V
AFS B1S1 or AFS B1 S1
(A/F)
-12.5%
Lean
More than 3.35 V
O2S B1 S2
(HO2)
+25%
Rich
 More than 0.55 V
O2S B1 S2
(HO2)
-12.5%
Lean
Less than 0.4 V

NOTICE:
The A/F sensor output has a few seconds of delay and the heated oxygen sensor output has about 20 seconds of delay at maximum.


Case
A/F Sensor (Sensor 1)
Output Voltage
HO2 Sensor (Sensor 2)
Output Voltage
Main Suspected Trouble Areas
1
Injection Volume
+25%
-12.5%
A103184
Injection Volume
+25%
-12.5%
A103184
-
Output Voltage
More than 3.35 V
Less than 3.0 V
A107708
Output Voltage
More than 0.55 V
Less than 0.4 V
A103186
2
Injection Volume
+25%
-12.5%
A103184
Injection Volume
+25%
-12.5%
A103184
  1. A/F sensor
  2. A/F sensor heater
  3. A/F sensor circuit
Output Voltage
Almost
no reaction
A103185
Output Voltage
More than 0.55 V
Less than 0.4 V
A103186
3
Injection Volume
+25%
-12.5%
A103184
Injection Volume
+25%
-12.5%
A103184
  1. HO2 sensor
  2. HO2 sensor heater
  3. HO2 sensor circuit
Output Voltage
More than 3.35 V
Less than 3.0 V
A107708
Output Voltage
Almost
no reaction
A103185
4
Injection volume
+25%
-12.5%
A103184
Injection Volume
+25%
-12.5%
A103184
  1. Injector
  2. Fuel pressure
  3. Gas leakage from exhaust system
    (Air-fuel ratio extremely lean or rich)
Output Voltage
Almost
no reaction
A103185
Output Voltage
Almost
no reaction
A103185
  1. The following A/F control procedure enables the technicians to check and graph the output voltages of both A/F Sensor and heated oxygen sensor.
  2. To display the graph, select the following menu items on the tester: View / Line graph.

HINT:
  1. 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 moving or stationary, 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.
  2. A low A/F sensor voltage could be caused by a rich air-fuel mixture. Check the conditions that would cause the engine to run with the rich air-fuel mixture.
  3. A high A/F sensor voltage could be caused by a lean air-fuel mixture. Check the conditions that would cause the engine to run with the lean air-fuel mixture.

1.INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)
G038638E03

  1. Disconnect the A18 sensor connector.

  1. Measure the resistance of the sensor.

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



NG
REPLACE AIR FUEL RATIO SENSOR
OK


2.INSPECT RELAY (Marking: A/F)
B060778E24

  1. Remove the A/F relay from the engine room relay block.

  1. Measure the resistance of the relay.

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



NG
REPLACE RELAY
OK


3.CHECK WIRE HARNESS (A/F SENSOR - ECM)
G038637E05

  1. Disconnect the A18 A/F sensor connector.

  1. Turn the E12 ECM connector.



  1. Measure the resistance of the wire harness side connectors.

    Standard resistance:
    Tester Connection
    		Specified Condition
    A18-1 (HT) - E12-1 (HA1A)
    		Below 1 Ω
    A18-3 (AF+) - E12-21 (A1A+)
    		Below 1 Ω
    A18-4 (AF-) - E12-31 (A1A-)
    		Below 1 Ω
    A18-1 (HT) or E12-1 (HA1A) - Body ground
    		10 kΩ or higher
    A18-3 (AF+) or E12-21 (A1A+) - Body ground
    		10 kΩ or higher
    A18-4 (AF-) or E12-31 (A1A-) - Body ground
    		10 kΩ or higher


    A112065E03



NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK

REPLACE ECM