P2237

2AR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P2237-P2239,P2252,P2253: Oxygen (A/F) Sensor Pumping Current Circuit / Open (Bank 1 Sensor 1)


DESCRIPTION

HINT
* Although the DTC titles say oxygen sensor, these DTCs relate to the air fuel ratio sensor.
* Sensor 1 refers to the sensor mounted in front of the three-way catalytic converter and located near the engine assembly.

The air fuel ratio sensor, which is located between the exhaust manifold and catalyst, consists of alloyed metal elements and a heater.

Depending on the engine operating conditions, the heater heats the sensor elements to activate them. Battery voltage is applied to the heater, and the sensor ground is controlled by the ECM using a duty ratio.

The sensor elements convert the oxygen concentration in the exhaust gas into voltage values to output. Based on the voltage, the ECM determines the air fuel ratio and regulates the fuel injection volume depending on the air fuel ratio and engine operating conditions. The voltage changes between 0.6 V and 4.5 V while the engine is running. If the air fuel ratio is lean, which means that the oxygen concentration in the exhaust gas is high, the voltage is high. If the air fuel ratio is rich, which means that the oxygen concentration in the exhaust gas is low, the voltage is low.













MONITOR DESCRIPTION

These DTCs are output when there is an open or short in the air fuel ratio sensor circuit, or if the air fuel ratio sensor output drops. To detect these problems, the voltage of the air fuel ratio sensor is monitored when turning the ignition switch to ON, and the admittance (admittance is an electrical term that indicates the ease of flow of current) is checked while driving. If the voltage of the air fuel ratio sensor is between 0.6 V and 4.5 V, it is considered normal. If the voltage is out of the specified range, or the admittance is less than the standard value, the ECM determines that there is a malfunction in the air fuel ratio sensor. If the same malfunction is detected in next driving cycle, the MIL is illuminated and a DTC is stored.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS

All





P2237 (Air Fuel Ratio Sensor Open Circuit Between A1A+ and A1A-)





P2238 (Air Fuel Ratio Sensor Low Impedance)





P2238 (Air Fuel Ratio Sensor Short Circuit Between A1A+ and A1A-, GND)





Other





TYPICAL MALFUNCTION THRESHOLDS

P2237 (Air Fuel Ratio Sensor Open Circuit Between A1A+ and A1A-)





P2238 (Air Fuel Ratio Sensor Low Impedance)





P2238 (Air Fuel Ratio Sensor Short Circuit Between A1A+ and GND)





P2239 (Air Fuel Ratio Sensor Short Circuit Between A1A+ and +B)





P2252 (Air Fuel Ratio Sensor Short Circuit Between A1A- and GND)





P2253 (Air Fuel Ratio Sensor Short Circuit Between A1A- and +B)





P2238 (Air Fuel Ratio Sensor Short Circuit Between A1A+ and A1A-)





COMPONENT OPERATING RANGE





CONFIRMATION DRIVING PATTERN





1. Connect the Techstream to the DLC3.

2. Turn the ignition switch to ON and turn the Techstream on.

3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure) Reading and Clearing Diagnostic Trouble Codes.

4. Turn the ignition switch off and wait for at least 30 seconds.

5. Turn the ignition switch to ON and turn the Techstream on [A].

6. Start the engine and wait 2 minutes.

7. Enter the following menus: Powertrain / Engine / Utility / All Readiness.

8. Input the DTC: P2237, P2238, P2239, P2252 or P2253.

9. Check the DTC judgment result [B].





HINT
* If the judgment result shows ABNORMAL, the system has a malfunction.
* If the judgment result shows INCOMPLETE or UNKNOWN, idle the engine for 3 minutes and check the DTC judgment result again [C].

10. If the test result is UNKNOWN, enter the following menus: Powertrain / Engine / Trouble Codes / Pending.

11. Read Pending DTCs.

HINT
If a pending DTC is output, the system is malfunctioning.

12. If the test result is INCOMPLETE or UNKNOWN and no pending DTC is output, perform a universal trip and check for permanent DTCs Reading and Clearing Diagnostic Trouble Codes.

HINT
* If a permanent DTC is output, the system is malfunctioning.
* If no permanent DTC is output, the system is normal.

WIRING DIAGRAM

Refer to DTC P2195 P2195.

INSPECTION PROCEDURE

HINT
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 sensor, heated oxygen 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 Techstream.

(a) Connect the Techstream to the DLC3.
(b) Start the engine.
(c) Turn the Techstream on.
(d) Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
(e) Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume for A/F Sensor.
(f) Perform the Active Test operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).
(g) Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2) displayed on the Techstream.

HINT
* The Control the Injection Volume for A/F Sensor 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.





NOTICE:
The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.





- Following the Control the Injection Volume for A/F Sensor procedure enables technicians to check and graph the voltage outputs of both the air fuel ratio and heated oxygen sensors.

- To display the graph, enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume for A/F Sensor / A/F Control System / AFS Voltage B1S1 and O2S B1S2; and then press the graph button on the Data List view.

HINT
Read freeze frame data using the Techstream. 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.

PROCEDURE

1. CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - ECM)

(a) Disconnect the air fuel ratio sensor connector.

(b) Disconnect the ECM connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance (Check for Open):





Standard Resistance (Check for Short):





(d) Reconnect the air fuel ratio sensor connector.

(e) Reconnect the ECM connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

2. REPLACE AIR FUEL RATIO SENSOR

(a) Replace the air fuel ratio sensor Removal.

NEXT -- Continue to next step.

3. PERFORM CONFIRMATION DRIVING PATTERN

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.

NEXT -- Continue to next step.

4. CHECK WHETHER DTC OUTPUT RECURS

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine / Trouble Codes / Pending.

(e) Read the pending DTCs.

Result:





B -- REPLACE ECM Removal

A -- END