- Open in Air Fuel Ratio (A/F) sensor (for Bank 1, 2 Sensor 1) circuit
- Air Fuel Ratio (A/F) sensor (for Bank 1, 2 Sensor 1)
- ECM
| Last Modified: 11-29-2007 | 1.6 C | |
| Service Category: Engine/Hybrid System | Section: Engine Control | |
| Model Year: 2008 | Model: Sequoia | Doc ID: RM000000XOK04BX |
| Title: 3UR-FE ENGINE CONTROL: SFI SYSTEM: DESCRIPTION (2008 Sequoia) | ||
|
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
Refer to DTC P2195
.
|
DTC No. |
DTC Detection Condition |
Trouble Area |
|---|---|---|
|
P2237 P2240 |
Open in the circuit between terminals AF+ and AF- 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 P2238, P2239, P2252 and P2253 indicate malfunctions related to the bank 1 A/F sensor circuit.
- DTCs P2241, P2242, P2255 and P2256 indicate malfunctions related to the 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 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 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 stored.
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
|
Related DTCs |
P2237: A/F sensor (for Bank 1) open circuit between AF+ and AF- P2238: A/F sensor (for Bank 1) short circuit between AF+ and AF- P2238: A/F sensor (for Bank 1) short circuit between AF+ and GND P2238: A/F sensor (for Bank 1) low impedance P2239: A/F sensor (for Bank 1) short circuit between AF+ and +B P2240: A/F sensor (for Bank 2) open circuit between AF+ and AF- P2241: A/F sensor (for Bank 2) short circuit between AF+ and AF- P2241: A/F sensor (for Bank 2) short circuit between AF+ and GND P2241: A/F sensor (for Bank 1) low impedance P2242: A/F sensor (for Bank 2) short circuit between AF+ and +B P2252: A/F sensor (for Bank 1) short circuit between AF- and GND P2253: A/F sensor (for Bank 1) short circuit between AF- and +B P2255: A/F sensor (for Bank 2) short circuit between AF- and GND P2256: A/F sensor (for 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: A/F sensor open circuit between AF+ and AF- and Low impedance 5 seconds: Other |
|
MIL Operation |
2 driving cycles |
|
Sequence of Operation |
None |
TYPICAL ENABLING CONDITIONS
All
|
Monitor runs whenever following DTCs not present |
P0031, P0032, P0051, P0052: A/F Sensor Heater P0102 - P0103: MAF sensor P0110 - P0113: IAT sensor P0115 - P0118: ECT sensor P0120 - P0223, P2135: TP sensor P0125: Insufficient ECT for Closed Loop 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: Air pump stuck On P2445: Air pump 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 1022°F) for P2237 and P2240 |
A/F Sensor - Low Impedance
|
Engine coolant temperature |
0°C (0°F) or higher |
|
Estimated sensor temperature |
700 to 800°C (1292 to 1472°F) for P2238 and P2241 |
|
Fuel cut |
Not executed |
Other
|
Battery voltage |
11 V or higher |
|
Ignition switch |
ON |
|
Timing after ignition switch off to ON |
5 seconds or more |
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- voltage |
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 |
WIRING DIAGRAM
Refer to DTC 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 (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 Techstream.
(a) Connect the Techstream to the DLC3.
(b) Start the engine and turn the Techstream on.
(c) Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.
(d) Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/ F sensor.
(e) Perform the Active Test 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 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.
Standard:
|
Tester Display (Sensor) |
Injection Volume |
Status |
Voltage |
|---|---|---|---|
|
AFS B1 S1 (A/F) |
+25% |
Rich |
Less than 3.0 |
|
-12.5% |
Lean |
More than 3.35 |
|
|
O2S B1 S2 (HO2) |
+25% |
Rich |
More than 0.55 |
|
-12.5% |
Lean |
Less than 0.4 |
|
|
AFS B2 S1 (A/F) |
+25% |
Rich |
Less than 3.0 |
|
-12.5% |
Lean |
More than 3.35 |
|
|
O2S B2 S2 (HO2) |
+25% |
Rich |
More than 0.55 |
|
-12.5% |
Lean |
Less than 0.4 |
NOTICE:
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.
|
Case |
A/F Sensor (Sensor 1) Output Voltage |
HO2 Sensor (Sensor 2) Output Voltage |
Main Suspected Trouble Area |
|---|---|---|---|
|
1 |
|
|
- |
|
2 |
|
|
|
|
3 |
|
|
|
|
4 |
|
|
|
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, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/ F Sensor / A/F Control System / AFS B1 S1 and O2S B1 S2 or AFS B2 S1 and O2S B2 S2.
HINT:
Read freeze frame data using the 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. |
CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM)
|
|
|
2. |
REPLACE AIR FUEL RATIO SENSOR |
(a) Replace the air fuel ratio sensor
.
|
|
3. |
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) Clear DTCs
.
(e) Start the engine.
(f) Allow the engine to idle for 5 minutes or more.
(g) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.
(h) Read pending DTCs.
Result
|
Result |
Proceed to |
|---|---|
|
No DTC is output |
A |
|
P2237, P2238, P2239, P2240, P2241, P2242, P2252, P2253, P2255 or P2256 is output |
B |
|
|
|