- Open or short in A/F sensor (bank 1, 2 sensor 1) circuit
- A/F sensor (bank 1, 2 sensor 1)
- ECM
| Last Modified: 7-3-2017 | 6.8:8.0.40 | Doc ID: RM000000XOK025X |
| Model Year Start: 2007 | Model: LX470 | Prod Date Range: [08/2006 - ] |
| Title: 2UZ-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); 2007 MY LX470 [08/2006 - ] | ||
|
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) |
DESCRIPTION
HINT:
- Although the DTC titles refer to the "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 is located near the engine assembly.
The A/F sensor consists of a heater and an element (made from several types of metal), and is located between the exhaust manifold and the catalyst.
Based on the engine condition, the heater activates the element by heating it. Battery voltage is applied to the heater. The voltage is controlled based on the duty signal.
The element outputs the exhaust gas's oxygen density as a voltage. The ECM derives the air-fuel ratio from this voltage. Then, according to the air-fuel ratio and engine condition, the fuel injection amount is adjusted. While the engine is running, the voltage varies between 0.6 to 4.5 V. When the exhaust gas's oxygen level is high (air-fuel ratio is lean), the voltage increases. When the exhaust gas's oxygen level is low (air-fuel ratio is rich), the voltage decreases.
Refer to DTC P2195
![2007 MY LX470 [08/2006 - ]; 2UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P2195-P2198; Oxygen (A/F) Sensor Signal Stuck Lean (Bank 1 Sensor 1)](../../../../stylegraphics/info.gif "2007 MY LX470 [08/2006 - ]; 2UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P2195-P2198; Oxygen (A/F) Sensor Signal Stuck Lean (Bank 1 Sensor 1)")
.
|
DTC No. |
DTC Detection Condition |
Trouble Area |
|---|---|---|
|
P2237 P2240 |
Open in the circuit between terminals A/F+ and A/F- of the A/F sensor while engine is running (2 trip detection logic) |
|
|
P2238 P2241 |
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
A/F sensor admittance: Less than 0.022 1/Ω (2 trip detection logic) |
|
|
P2239 P2242 |
AF+ voltage more than 4.5 V for 5.0 seconds or more (2 trip detection logic) |
|
|
P2252 P2255 |
AF- voltage 0.5 V or less for 5.0 seconds or more (2 trip detection logic) |
|
|
P2253 P2256 |
AF- voltage more than 4.5 V for 5.0 seconds or more (2 trip detection logic) |
|
HINT:
- DTCs P2237, P2238, P2239, P2252 and P2253 indicate malfunctions related to bank 1 A/F sensor circuit.
- DTCs P2240, P2241, P2242, P2255 and P2256 indicate malfunctions related to bank 2 A/F sensor circuit.
- Bank 1 refers to the bank that includes No. 1 cylinder.
- Bank 2 refers to the bank that includes No. 2 cylinder.
MONITOR DESCRIPTION
These DTCs are output when there is an open or short in the A/F sensor circuit, or if A/F sensor output drops.
To detect these problems, the voltage of the A/F sensor is monitored when turning the ignition switch to the ON position, 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 A/F sensor is between 0.6 V and 4.5 V, it is considered normal. If the voltage is outside of the specified range, or the admittance is less than the standard value, the ECM will determine that there is a malfunction in the A/F sensor. If the same malfunction is detected in the next driving cycle, the MIL is illuminated and a DTC is set.
MONITOR STRATEGY
|
Related DTCs |
P2237: A/F sensor (Bank 1) open circuit between AF+ and AF- P2238: A/F sensor (Bank 1) low impedance P2238: A/F sensor (Bank 1) short circuit between AF+ and AF- P2238: A/F sensor (Bank 1) short circuit between AF+ and GND P2239: A/F sensor (Bank 1) short circuit between AF+ and +B P2240: A/F sensor (Bank 2) open circuit between AF+ and AF- P2241: A/F sensor (Bank 2) low impedance P2241: A/F sensor (Bank 2) short circuit between AF+ and AF- P2241: A/F sensor (Bank 2) short circuit between AF+ and GND P2242: A/F sensor (Bank 2) short circuit between AF+ and +B P2252: A/F sensor (Bank 1) short circuit between AF- and GND P2253: A/F sensor (Bank 1) short circuit between AF- and +B P2255: A/F sensor (Bank 2) short circuit between AF- and GND P2256: A/F sensor (Bank 2) short circuit between AF- and +B |
|
Required Sensors/Components (Main) |
A/F sensor |
|
Required Sensors/Components (Related) |
Engine Coolant Temperature (ECT) sensor, Crankshaft position sensor |
|
Frequency of Operation |
Once per driving cycle |
|
Duration |
10 seconds |
|
MIL Operation |
2 driving cycle |
|
Sequence of Operation |
None |
TYPICAL ENABLING CONDITIONS
All:
|
Monitor runs whenever following DTCs not present |
P0031, P0032, P0051, P0052: A/F sensor heater P0100 - P0103: MAF sensor P0110 - P0113: IAT sensor P0115 - P0118, P0125: ECT sensor P0120 - P0223, P2135: TP sensor P0171 - P0175: Fuel trim P0300 - P0308: Misfire P0335: CKP sensor P0455, P0456: EVAP system P0500: VSS P2440: AIR control valve stuck open P2441: AIR control valve stuck close P2444: AIP stuck On P2445: AIP stuck Off |
A/F sensor - open circuit between AF+ and AF-
|
Battery voltage |
11 V or more |
|
Engine |
Running |
|
Estimated sensor temperature |
450 to 550°C (842 to 1,022°F) for P2237 and P2240 |
A/F sensor - Low impedance
|
Engine coolant temperature |
0°C (0°F) or higher [Closed loop enabling ECT] |
|
Estimated sensor temperature |
700 to 800°C (1,292 to 1,472°F) for P2238 and P2241 |
|
Fuel cut |
Not executed |
Other:
|
Battery voltage |
11 V or higher |
|
Ignition switch |
ON |
|
Timing after ignition switch is OFF to ON |
5 seconds |
TYPICAL MALFUNCTION THRESHOLDS
P2237 and P2240:
|
A/F sensor admittance |
Below 0.002 1/Ω |
P2238 and P2241:
|
When one of following conditions is met: |
Condition 1, 2 or 3 |
|
1. Sensor admittance |
Less than 0.022 1/Ω |
|
2. AF+ voltage |
0.5 V or less |
|
3. Difference of AF+ and AF- |
0.1 V or less |
P2239 and P2242:
|
AF+ voltage |
More than 4.5 V |
P2252 and P2255:
|
AF- voltage |
0.5 V or less |
P2253 and P2256:
|
AF- voltage |
More than 4.5 V |
COMPONENT OPERATING RANGE
|
Sensor admittance |
0.022 1/Ω or more |
|
AF+ voltage |
0.6 to 4.5 V |
|
AF- voltage |
0.6 to 4.5 V |
|
Difference of AF+ and AF- |
0.11 to 0.8 V |
WIRING DIAGRAM
Refer to DTC P2195 (
).
INSPECTION PROCEDURE
HINT:
Intelligent tester only:
Malfunctioning areas can be identified by performing the A/F CONTROL function provided in the ACTIVE TEST. The A/F CONTROL 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 A/F CONTROL operation using the intelligent tester.
- Connect the intelligent tester to the CAN VIM. Then connect the CAN VIM 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: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
- Perform the A/F CONTROL 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 B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2) 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.
Standard:
|
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% |
|
|
|
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% |
|
|
|
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% |
|
|
|
Output Voltage Almost no reaction |
|
Output Voltage Almost no reaction |
|
||
- Following the A/F CONTROL procedure enables technicians to check and graph the output voltages of both the A/F and HO2 sensors.
- To display the graph, enter the following menus: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL / USER DATA / AFS B1S1 and O2S B1S2 or AFS B2S1 and O2S B2S2. Then press the YES button and ENTER button, followed by the F4 button.
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 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. |
CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM) |
(a)
Check the harness and connector
.
| NG |
|
|
|
2. |
REPLACE AIR FUEL RATIO SENSOR |
|
|
3. |
CHECK WHETHER DTC OUTPUT RECURS |
(a) Connect the intelligent tester to the DLC3.
(b) Turn the ignition switch to the ON position and turn the tester ON.
(c)
Clear the DTCs
.
(d) Start the engine.
(e) Allow the engine to idle for 5 minutes or more.
(f) Select the following menu items: DIAGNOSIS / ENHANCED OBD II / DTC INFO / PENDING CODES.
(g) Read pending DTCs.
|
Display (DTC Output) |
Proceed to |
|---|---|
|
No output |
A |
|
P2237, P2238, P2239, P2240, P2241, P2242, P2252, P2253, P2255 or P2256 |
B |
| B |
|
| A |
|
|
|