P2255
2GR-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P2237: 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
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 of 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 air-fuel ratio 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.
In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a TWC is used. For the most efficient use of the TWC, the air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric level.
*: Value changes inside the ECM. Since the A/F sensor is the current output element, a current is converted into a voltage inside the ECM. Any measurements taken at the A/F sensor or ECM connectors will show a constant voltage.
HINT:
- DTCs P2237, P2238, P2239, P2252 and P2253 indicate malfunctions related to the bank 1 A/F sensor circuit.
- DTCs P2240, P2241, P2242, P2255 and P2256 indicate malfunctions related to the 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.
- When either of these DTCs is set, check the A/F sensor output voltage by selecting the following menu items on Techstream: Powertrain / Engine and ECT / Data List / A/F Control System / AFS B1 S1 or AFS B2 S1.
- Short-term fuel trim values can also be read using Techstream.
- The ECM regulates the voltages at the A1A+ and A1A- or A2A+ and A2A- terminals of the ECM to a constant level. Therefore, the A/F sensor output voltage cannot be confirmed without using Techstream.
- If the A/F sensor is malfunctioning, the ECM sets the DTC.
MONITOR DESCRIPTION
The Air-Fuel Ratio (A/F) sensor varies its output voltage in proportion to the air-fuel ratio. If the A/F sensor impedance (alternating current resistance) or output voltage deviates greatly from the standard range, the ECM determines that there is an open or short in the A/F sensor circuit.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
P2237 and P2240 (Air fuel ratio sensor open circuit between AF+ and AF-):
P2238 and P2241 (open circuit between AF+ and AF-):
Other:
TYPICAL MALFUNCTION THRESHOLDS
P2237 and P2240 (Open circuit between AF+ and AF-):
P2238 and P2241 (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
INSPECTION PROCEDURE
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.
HINT: Techstream 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 Techstream.
(a) Connect Techstream to the DLC3.
(b) Start the engine and turn the tester ON.
(c) Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
(d) On the tester, select the following menu items: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.
(e) Perform the Control the Injection Volume for A/F Sensor operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).
(f) 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 Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 25%.
- The sensors react in accordance with increases and decreases in the fuel injection volume.
Standard:
NOTE: The A/F sensor has an output delay of a few seconds and the HO2 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 output voltages of both the A/F and HO2 sensors.
- To display the graph, select the following menu items on the tester: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / A/F Control System / AFS B1 S1 or AFS B2 S1 and O2S B1 S2 or O2S B2 S2 then press the graph button on the Data List view.
HINT: Read freeze frame data using Techstream. Freeze frame data records the engine condition 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.
PROCEDURE
1. INSPECT AIR-FUEL RATIO SENSOR (HEATER RESISTANCE) P0031
NG -- REPLACE AIR-FUEL RATIO SENSOR
OK -- Continue to next step.
2. INSPECT INTEGRATION RELAY (A/F RELAY) P0031
NG -- REPLACE INTEGRATION RELAY
OK -- Continue to next step.
3. CHECK WIRE HARNESS (A/F SENSOR - ECM) P2195
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
4. REPLACE AIR-FUEL RATIO SENSOR
NEXT -- Continue to next step.
5. PERFORM CONFIRMATION DRIVING PATTERN
(a) Drive the vehicle referring the Confirmation Driving Pattern on DTC P2195 P2195
NEXT -- Continue to next step.
6. CHECK WHETHER DTC OUTPUT RECURS
(a) Connect Techstream to the DLC3.
(b) Turn the ignition switch ON and turn the tester ON.
(c) Clear DTCs DTC Check / Clear.
(d) Select the following menu items: Powertrain / Engine and ECT / Trouble Code / Pending.
(e) Read pending DTCs.
Result:
B -- REPLACE ECM
A -- END