Last Modified: 4-30-2014 6.6 C Doc ID: RM000000XOK00JX
Model Year: 2006 Model: LX470 Prod Date Range: [05/2005 -           ]
Title: 2UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P2238,P2239,P2241,P2242,P2252,P2253,P2255,P2256; Oxygen (A/F) Sensor Pumping Current Circuit Low (Bank 1 Sensor 1); 2006 MY LX470 [05/2005 -        ]

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

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.

Refer to DTC P2195 2006 MY LX470 [05/2005 -        ]; 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

P2238

P2241
  • Case 1:

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

  • Case 2:

A/F sensor admittance: Less than 0.022 1/Ω

(2 trip detection logic)
  • Open or short in Air Fuel Ratio (A/F) sensor (bank 1, 2 sensor 1) circuit
  • Air Fuel Ratio (A/F) sensor (bank 1, 2 sensor 1)
  • Air Fuel Ratio (A/F) sensor heater (bank 1, 2 sensor 1)
  • A/F relay
  • A/F sensor heater and relay circuits
  • ECM

P2239

P2242

AF+ voltage more than 4.5 V for 5.0 seconds or more

(2 trip detection logic)
  • Open or short in A/F sensor (bank 1, 2 sensor 1) circuit
  • A/F sensor (bank 1, 2 sensor 1)
  • A/F sensor heater (bank 1, 2 sensor 1)
  • A/F relay
  • A/F sensor heater and relay circuits
  • ECM

P2252

P2255

AF- voltage 0.5 V or less for 5.0 seconds or more

(2 trip detection logic)
  • Open or short in A/F sensor (bank 1, 2 sensor 1) circuit
  • A/F sensor (bank 1, 2 sensor 1)
  • A/F sensor heater (bank 1, 2 sensor 1)
  • A/F relay
  • A/F sensor heater and relay circuits
  • ECM

P2253

P2256

AF- voltage more than 4.5 V for 5.0 seconds or more

(2 trip detection logic)
  • Open or short in A/F sensor (bank 1, 2 sensor 1) circuit
  • A/F sensor (bank 1, 2 sensor 1)
  • A/F sensor heater (bank 1, 2 sensor 1)
  • A/F relay
  • A/F sensor heater and relay circuits
  • ECM

HINT:

  • DTCs P2238, P2239, P2252 and P2253 indicate malfunctions related to bank 1 A/F sensor circuit.
  • DTCs 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

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 malfunction in the A/F sensor circuit.

MONITOR STRATEGY

Related DTCs

P2238: A/F sensor (Bank 1) open circuit between AF+ and AF-

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

P2241: A/F sensor (Bank 2) open circuit between AF+ and AF-

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: A/F sensor open circuit between AF+ and AF-

5 seconds: Others

MIL Operation

2 driving cycle

Sequence of Operation

None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever following DTCs not present

None

P2238 and P2241 (open circuit between AF+ and AF-):

Duration while all of following conditions met

-

AF+ terminal voltage

0.5 to 4.5 V

AF- terminal voltage

0.5 to 4.5 V

Difference between AF+ and AF- terminal voltages

0.1 to 0.8 V

ECT

20°C (68°F) or more

Engine condition

Running

Time after engine start

50 seconds or more

Fuel-cut

OFF

A/F sensor heater duty ratio

0% or more

Time after A/F sensor heating

20 seconds or more

Battery voltage

10.5 V or more

Ignition switch

ON

Others:

Battery voltage

10.5 V or more

Ignition switch

ON

TYPICAL MALFUNCTION THRESHOLDS

P2238 and P2241 (Open circuit between AF+ and AF-):

A/F sensor admittance

Below 0.022 1/Ω

P2238 and P2241 (Short circuit between AF+ and GND):

AF+ terminal voltage

0.5 V or less

P2238 and P2241 (Short circuit between AF+ and AF-):

Difference between AF+ and AF- terminal voltages

0.1 V or less

P2239 and P2242 (Short circuit between AF+ and +B):

AF+ terminal voltage

More than 4.5 V

P2252 and P2255 (Short circuit between AF- and GND):

AF- terminal voltage

0.5 V or less

P2253 and P2256 (Short circuit between AF- and +B):

AF- terminal voltage

More than 4.5 V

WIRING DIAGRAM

Refer to DTC P2195 ( 2006 MY LX470 [05/2005 -        ]; 2UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P2195-P2198; Oxygen (A/F) Sensor Signal Stuck Lean (Bank 1 Sensor 1)+ ).

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.

  1. Connect the intelligent tester to the CAN VIM. Then connect the CAN VIM to the DLC3.
  2. Start the engine and turn the tester ON.
  3. Warm up the engine at an engine speed of 2,500 rpm for approximately 90 seconds.
  4. On the tester, enter the following menus: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL.
  5. 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).
  6. 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%
  • A/F sensor
  • A/F sensor heater
  • A/F sensor circuit

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%
  • HO2 sensor
  • HO2 sensor heater
  • HO2 sensor circuit

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%
  • Fuel injector
  • Fuel pressure
  • Gas leakage from exhaust system

    (Air fuel ratio extremely lean or rich)

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.

INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)

(a) Disconnect the A53 or A54 Air Fuel Ratio (A/F) sensor connector.

(b) Measure the resistance of the A/F sensor connector.

Standard resistance:

Tester Connection

Specified Condition

HT (1) - +B (2)

1.8 to 3.4 Ω at 20°C (68°F)

HT (1) - AF- (4)

10 kΩ or higher

(c) Reconnect the A/F sensor connector.
NG

REPLACE AIR FUEL RATIO SENSOR

OK

2.

INSPECT A/F RELAY (Marking: A/F HTR)

(a) Remove the A/F relay from the No. 8 engine room relay block.

(b) Measure the resistance of the A/F relay.

Standard resistance:

Tester Connection

Specified Condition

3 - 5

10 kΩ or higher

3 - 5

Below 1 Ω

(when battery voltage applied to terminals 1 and 2)

(c) Reinstall the A/F relay.
NG

REPLACE A/F RELAY

OK

3.

CHECK HARNESS AND CONNECTOR (A/F SENSOR - ECM)

(a) Check harness and connector 2006 MY LX470 [05/2005 -        ]; INTRODUCTION: HOW TO TROUBLESHOOT ECU CONTROLLED SYSTEMS: ELECTRONIC CIRCUIT INSPECTION PROCEDURE .

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

REPLACE ECM