P2238

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.
   

Refer to DTC P2195 (Click here).

DTC No.	DTC Detection Condition	Trouble Area
P2238 P2241	Case 1: Condition (a) or (b) continues for 5.0 seconds or more (1 trip detection logic): (a) AF+ voltage 0.5 V or less (b) (AF+) - (AF-) = 0.1 V or less Case 2: A/F sensor admittance: Less than 0.022 1/Ω (2 trip detection logic)	Open or short in A/F sensor (bank 1, 2 sensor 1) circuit A/F sensor (bank 1, 2 sensor 1) A/F sensor heater A/F HTR relay A/F sensor heater and relay circuits ECM
P2239 P2242	AF+ voltage more than 4.5 V for 5.0 seconds or more (2 trip detection logic)	Open or short in A/F sensor (bank 1, 2 sensor 1) circuit A/F sensor (bank 1, 2 sensor 1) A/F sensor heater A/F HTR relay A/F sensor heater and relay circuits ECM
P2252 P2255	AF- voltage 0.5 V or less for 5.0 seconds or more (2 trip detection logic)	Open or short in A/F sensor (bank 1, 2 sensor 1) circuit A/F sensor (bank 1, 2 sensor 1) A/F sensor heater A/F HTR relay A/F sensor heater and relay circuits ECM
P2253 P2256	AF- voltage more than 4.5 V for 5.0 seconds or more (2 trip detection logic)	Open or short in A/F sensor (bank 1, 2 sensor 1) circuit A/F sensor (bank 1, 2 sensor 1) A/F sensor heater A/F HTR relay A/F sensor heater and relay circuits ECM

HINT:

1. DTCs P2238, P2239, P2252 and P2253 indicate malfunctions related to bank 1 A/F sensor circuit.
   
2. DTCs P2241, P2242, P2255 and P2256 indicate malfunctions related to bank 2 A/F sensor circuit.
   
3. Bank 1 refers to the bank that includes cylinder No. 1.
   
4. Bank 2 refers to the bank that includes cylinder No. 2.
   

WIRING DIAGRAM

Refer to DTC P2195 (Click here).

INSPECTION PROCEDURE

HINT:

Intelligent tester only:

Malfunctioning areas can be identified by performing the Control the Injection Volume for A/F Sensor function provided in the Active Test. The Control the Injection Volume for A/F Sensor function can help to determine whether the Air-Fuel Ratio (A/F) sensor, Heated Oxygen (HO2) sensor and other potential trouble areas are malfunctioning.

The following instructions describe how to conduct the Control the Injection Volume for A/F Sensor operation using the intelligent tester.

1. Connect the intelligent tester to the DLC3.
   
2. Start the engine and turn the tester ON.
   
3. Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
   
4. On the tester, enter the following menus: Power train / Engine / Active Test / Control the Injection Volume for A/F Sensor.
   
5. Perform the Control the Injection Volume for A/F Sensor operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).
   
6. Monitor the output voltages of the A/F and HO2 sensors (AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2) displayed on the tester.
   

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.
   

Tester Display (Sensor)	Injection Volume	Status	Voltage
AFS B1S1 or AFS B2S1 (A/F)	+25 %	Rich	Less than 3.0
AFS B1S1 or AFS B2S1 (A/F)	-12.5 %	Lean	More than 3.35
O2S B1S2 or O2S B2S2 (HO2)	+25 %	Rich	More than 0.55
O2S B1S2 or O2S B2S2 (HO2)	-12.5 %	Lean	Less than 0.4

NOTICE:

The Air-Fuel Ratio (A/F) sensor has an output delay of a few seconds and the Heated Oxygen (HO2) sensor has a maximum output delay of approximately 20 seconds.

Case	A/F Sensor (Sensor 1) Output Voltage		HO2 Sensor (Sensor 2) Output Voltage		Main Suspected Trouble Areas
1	Injection Volume +25 % -12.5 %		Injection Volume +25 % -12.5 %		-
	Output Voltage More than 3.35 V Less than 3.0 V		Output Voltage More than 0.55 V Less than 0.4 V
2	Injection Volume +25 % -12.5 %		Injection Volume +25 % -12.5 %		A/F sensor A/F sensor heater A/F sensor circuit
	Output Voltage Almost no reaction		Output Voltage More than 0.55 V Less than 0.4 V
3	Injection Volume +25 % -12.5 %		Injection Volume +25 % -12.5 %		HO2 sensor HO2 sensor heater HO2 sensor circuit
	Output Voltage More than 3.35 V Less than 3.0 V		Output Voltage Almost no reaction
4	Injection volume +25 % -12.5 %		Injection Volume +25 % -12.5 %		Injector Fuel pressure Gas leakage from exhaust system (Air-fuel ratio extremely lean or rich)
	Output Voltage Almost no reaction		Output Voltage Almost no reaction

1. Following the A/F CONTROL procedure enables technicians to check and graph the output voltages of both the A/F and HO2 sensors.
   
2. The following A/F Control procedure enables the technician to check and graph the voltage output of both the heated oxygen sensors. 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 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 (Click here).
   

1. INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

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

2. 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 Ω
   HA1A (1) - A1A- (4)	-	10 kΩ 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 Ω
   HA2A (1) - A2A- (4)	-	10 kΩ or higher

3. Reconnect the A/F sensor connector.

NG	REPLACE AIR FUEL RATIO SENSOR

OK

2. INSPECT A/F HTR RELAY

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

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

   Standard resistance:

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

3. Reinstall the A/F HTR relay.

NG	REPLACE A/F HTR RELAY

OK

3. CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM)

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

2. Turn the engine switch on (IG).

3. Measure the voltage between the +B terminal of the A/F sensor connector and body ground.

   Standard voltage:

   Tester Connection	Specified Condition
   +B (E38-2) - Body ground	9 to 14 V
   +B (E42-2) - Body ground	9 to 14 V

4. Turn the engine switch off.

5. Disconnect the E6 ECM connector.

6. Check 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 Ω
   A1A+ (E42-3) - A1A+ (E6-18)	Below 1 Ω
   A1A- (E42-4) - A1A- (E6-17)	Below 1 Ω
   HA2A (E38-1) - HA2A (E6-4)	Below 1 Ω
   A2A+ (E38-3) - A2A+ (E6-28)	Below 1 Ω
   A2A- (E38-4) - A2A- (E6-27)	Below 1 Ω

   Standard resistance (Check for short):

   Tester Connection	Specified Condition
   HA1A (E42-1) or HA1A (E6-6) - Body ground	10 kΩ or higher
   A1A+ (E42-3) or A1A+ (E6-18) - Body ground	10 kΩ or higher
   A1A- (E42-4) or A1A- (E6-17) - Body ground	10 kΩ or higher
   HA2A (E38-1) or HA2A (E6-4) - Body ground	10 kΩ or higher
   A2A+ (E38-3) or A2A+ (E6-28) - Body ground	10 kΩ or higher
   A2A- (E38-4) or A2A- (E6-27) - Body ground	10 kΩ or higher

7. Reconnect the ECM connector.

8. Reconnect the A/F sensor connector.
   

NG	REPAIR OR REPLACE HARNESS OR CONNECTOR

OK
REPLACE ECM