P2239
2GR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P2237-P2239,P2240-P2242,P2252,P2253,P2255,P2256: Oxygen (A/F) Sensor Pumping Current Circuit / Open (Bank 1 Sensor 1)
DTC P2237 - Oxygen (A/F) Sensor Pumping Current Circuit / Open (Bank 1 Sensor 1)
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 P2240 - Oxygen (A/F) Sensor Pumping Current Circuit / Open (Bank 2 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)
CAUTION / NOTICE / HINT
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.
DESCRIPTION
The A/F sensor generates a voltage* that corresponds to the actual air-fuel ratio. This sensor voltage is used to provide the ECM with feedback so that it can control the air-fuel ratio. The ECM determines the deviation from the stoichiometric air-fuel ratio level, and regulates the fuel injection time. If the A/F sensor malfunctions, the ECM is unable to control the air-fuel ratio accurately.
The A/F sensor is the planar type and is integrated with the heater, which heats the solid electrolyte (zirconia element). This heater is controlled by the ECM. When the intake air volume is low (the exhaust gas temperature is low), a current flows into the heater to heat the sensor, in order to facilitate accurate oxygen concentration detection. In addition, the sensor and heater portions are narrower than the conventional type. The heat generated by the heater is conducted to the solid electrolyte through the alumina, therefore the sensor activation is accelerated.
A three-way catalytic converter (TWC) is used in order to convert the carbon monoxide (CO), hydro carbon (HC), and nitrogen oxides (HOx) into less harmful substances. To allow the TWC to function effectively, it is necessary to keep the air-fuel ratio of the engine near the stoichiometric air-fuel ratio.
*: Value changes inside the ECM. Since the A/F sensor is the current output element, a current is converted to a voltage inside the ECM. Any measurements taken at the A/F sensor or ECM connectors will show a constant voltage.
HINT:
- DTC P2237, P2238, P2239, P2252 and P2253 indicate malfunctions related to the bank 1 air fuel ratio sensor circuit.
- DTC P2240, P2241, P2242, P2255 and P2256 indicate malfunctions related to the bank 2 air fuel ratio sensor circuit.
- Bank 1 refers to the bank that includes cylinder No. 1.
- Bank 2 refers to the bank that includes cylinder No. 2.
MONITOR DESCRIPTION
The air fuel ratio sensor varies its output voltage in proportion to the air fuel ratio. If the air fuel ratio sensor impedance (alternating current resistance) or voltage output deviates greatly from the standard range, the ECM determines that there is an open or short malfunction in the air fuel ratio sensor circuit.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
P2237 and P2240 (Air fuel ratio sensor open circuit between AF+ and AF-):
P2238 and P2241 (Low admittance):
Others:
TYPICAL MALFUNCTION THRESHOLDS
P2237 and P2240 (Open circuit between AF+ and AF-):
P2238 and P2241 (Short circuit between AF+ and GND):
P2238 and P2241 (Short circuit between AF+ and AF-):
P2239 and P2242 (Short circuit between AF+ and +B):
P2252 and P2255 (Short circuit between AF- and GND):
P2253 and P2256 (Short circuit between AF- and +B):
WIRING DIAGRAM
CONFIRMATION DRIVING PATTERN
This confirmation driving pattern is used in steps 4, 7, 17, and 21 of the following diagnostic troubleshooting procedure when using the Techstream.
1 Connect the Techstream to the DLC3 (Procedure "A").
2 Turn the ignition switch to ON (Procedure "B").
3 Turn the Techstream on (Procedure "C").
4 Clear the DTCs DTC Check / Clear (Procedure "D").
5 Start the engine, and warm it up until the ECT reaches 70°C (158°F) or higher (Procedure "E").
6 Select the following menu items on the Techstream to check the fuel-cut status: Powertrain / Engine and ECT / Data List / Idle Fuel Cut (Procedure "F").
7 Drive the vehicle at between 38 mph (60 km/h) and 75 mph (120 km/h) for at least 10 minutes (Procedure "G").
8 Change the transmission to the 2nd gear (Procedure "H").
9 Drive the vehicle at a proper vehicle speed to perform fuel-cut operation (refer to the following HINT) (Procedure "I").
HINT:
Fuel-cut is performed when the following conditions are met:
- Accelerator pedal is fully released.
- Engine speed is 2,500 rpm or more (fuel injection resumes at 1,000 rpm).
10 Accelerate the vehicle to 40 mph (64 km/h) or more by depressing the accelerator pedal for at least 10 seconds (Procedure "J").
11 Soon after performing procedure "J", release the accelerator pedal for at least 4 seconds without depressing the brake pedal, in order to execute fuel-cut control (Procedure "K").
12 Allow the vehicle to decelerate until the vehicle speed declines to less than 6 mph (10 km/h) (Procedure "L").
13 Repeat procedures from "H" through "K" in this information at least 3 times per driving cycle (Procedure "M").
HINT: Completion of all A/F sensor monitors is required to change the value in TEST RESULT.
CAUTION:
Strictly observe posted speed limits, traffic laws, and road conditions when performing these driving patterns.
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.
1 Connect the Techstream to the DLC3.
2 Start the engine and turn the Techstream on.
3 Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
4 Select the following menu items: Powertrain / Engine and ECT / 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 voltage outputs of the air fuel ratio and heated oxygen sensors (AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2) displayed on the tester.
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.
Standard voltage:
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.
PROCEDURE
1. CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR - ECM)
(a) Disconnect the A/F sensor connector.
(b) Turn the ignition switch to ON.
(c) Measure the voltage between the +B terminal of the A/F sensor connector and body ground.
Standard voltage:
(d) Turn the ignition switch off.
(e) Disconnect the ECM connector.
(f) Measure the resistance between the terminals of A/F sensor connector and ECM connector.
Standard resistance :
Check for open
Check for short
(g) Reconnect the ECM connector.
(h) Reconnect the A/F sensor connector.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (AIR FUEL RATIO SENSOR - ECM)
OK -- Continue to next step.
2. REPLACE AIR FUEL RATIO SENSOR
(a) Replace the air fuel ratio sensor Components.
NEXT -- Continue to next step.
3. PERFORM CONFIRMATION DRIVING PATTERN
(a) Drive the vehicle referring the Confirmation Driving Pattern on DTC P2195 P2195.
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) Select the following menu items: Powertrain / Engine and ECT / Trouble Codes.
(e) Read DTCs.
Result:
B -- REPLACE ECM
A -- END