INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)
CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM)
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 P2241 Oxygen (A/F) Sensor Pumping Current Circuit Low (Bank 2 Sensor 1)
DTC P2242 Oxygen (A/F) Sensor Pumping Current Circuit High (Bank 2 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)
DTC P2255 Oxygen (A/F) Sensor Reference Ground Circuit Low (Bank 2 Sensor 1)
DTC P2256 Oxygen (A/F) Sensor Reference Ground Circuit High (Bank 2 Sensor 1)
Description
HINT:
- Although the DTC titles say oxygen sensor, these DTCs relate to the Air-Fuel Ratio (A/F) sensor.
- 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 .
| DTC No. | DTC Detection Condition | Trouble Area |
| P2238 P2241 |
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| P2239 P2242 |
AF+ voltage more than 4.5 V for 5.0 seconds or more (2 trip detection logic) |
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| P2252 P2255 |
AF- voltage 0.5 V or less for 5.0 seconds or more (2 trip detection logic) |
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| P2253 P2256 |
AF- voltage more than 4.5 V for 5.0 seconds or more (2 trip detection logic) |
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HINT:
- DTCs P2238, P2239, P2252 and P2253 indicate malfunctions related to bank 1 A/F sensor circuit.
- DTCs P2241, P2242, P2255 and P2256 indicate malfunctions related to bank 2 A/F sensor circuit.
- Bank 1 refers to the bank that includes cylinder No. 1.
- Bank 2 refers to the bank that includes cylinder No. 2.
Wiring diagram
Refer to DTC P2195.
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.
- Connect the intelligent tester to the DLC3.
- Start the engine and turn the tester ON.
- Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
- On the tester, enter the following menus: Power train / Engine / Active Test / Control the Injection Volume for A/F Sensor.
- 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).
- 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:
- The A/F CONTROL operation lowers the fuel injection volume by 12.5 % or increases the injection volume by 25 %.
- 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 |
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Output Voltage More than 0.55 V Less than 0.4 V |
 |
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| 2 | Injection Volume +25 % -12.5 % |
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Injection Volume +25 % -12.5 % |
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| Output Voltage Almost no reaction |
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Output Voltage More than 0.55 V Less than 0.4 V |
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| 3 | Injection Volume +25 % -12.5 % |
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Injection Volume +25 % -12.5 % |
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| Output Voltage More than 3.35 V Less than 3.0 V |
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Output Voltage Almost no reaction |
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| 4 | Injection volume +25 % -12.5 % |
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Injection Volume +25 % -12.5 % |
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| Output Voltage Almost no reaction |
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Output Voltage Almost no reaction |
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- Following the A/F CONTROL procedure enables technicians to check and graph the output voltages of both the A/F and HO2 sensors.
- 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:
- 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) |
-
Disconnect the E38 or E42 A/F sensor connector.
-
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
-
Reconnect the A/F sensor connector.
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| OK | |
| 2.INSPECT A/F HTR RELAY |
-
Remove the A/F HTR relay from the engine room J/B and R/B No. 2.
-
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)
-
Reinstall the A/F HTR relay.
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| OK | |
| 3.CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM) |
-
Disconnect the E38 or E42 A/F sensor connector.
-
Turn the engine switch on (IG).
-
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
-
Turn the engine switch off.
-
Disconnect the E6 ECM connector.
-
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 ? A1A+ (E42-3) - A1A+ (E6-18) Below 1 ? A1A- (E42-4) - A1A- (E6-17) Below 1 ? HA2A (E38-1) - HA2A (E6-4) Below 1 ? A2A+ (E38-3) - A2A+ (E6-28) Below 1 ? A2A- (E38-4) - A2A- (E6-27) Below 1 ? Standard resistance (Check for short):
Tester Connection Specified Condition HA1A (E42-1) or HA1A (E6-6) - Body ground 10 k? or higher A1A+ (E42-3) or A1A+ (E6-18) - Body ground 10 k? or higher A1A- (E42-4) or A1A- (E6-17) - Body ground 10 k? or higher HA2A (E38-1) or HA2A (E6-4) - Body ground 10 k? or higher A2A+ (E38-3) or A2A+ (E6-28) - Body ground 10 k? or higher A2A- (E38-4) or A2A- (E6-27) - Body ground 10 k? or higher
-
Reconnect the ECM connector.
-
Reconnect the A/F sensor connector.
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| OK | ||
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