Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Exhaust Gas Sensor Circuit (B1418/18)

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Vehicle Interior / Heating / Air Conditioning / Air Conditioning System / Exhaust Gas Sensor Circuit (B1418/18)

DESCRIPTION

The smog ventilation sensor is installed to the front of the cooler condenser assembly to automatically control the air inlet mode (fresh, recirculation/fresh, and recirculation).

This sensor detects HC and CO in the ambient air and transmits signals to the air conditioning amplifier assembly.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Memory

B1418/18

Exhaust Gas Sensor Circuit

Open or short in smog ventilation sensor circuit (HC, CO) (w/ Smog Ventilation Sensor)
  • Smog ventilation sensor
  • Harness or connector between smog ventilation sensor and IG power source
  • Harness or connector between smog ventilation sensor and body ground
  • Harness or connector between smog ventilation sensor and air conditioning amplifier assembly
  • Air conditioning amplifier assembly

-

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

  • Inspect the fuses for circuits related to this system before performing the following procedure.
  • If DTCs B1418/18 and B1461/61 are stored simultaneously, there may be a malfunction in the smog ventilation sensor power source circuit.

PROCEDURE

1.

READ VALUE USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Turn the Techstream on.

(d) Allow exhaust gas (HC, CO) to travel to the sensing portion of the smog ventilation sensor.

(e) Enter the following menus: Body Electrical / Air Conditioner / Data List.

(f) Read the Data List according to the display on the Techstream.

Body Electrical > Air Conditioner > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Emission Gas Sensor

Emission gas (HC, CO)

Min.: 0

Max.: 255

Smog ventilation sensor value increases as gas amount increases

-
Body Electrical > Air Conditioner > Data List

Tester Display

Emission Gas Sensor

OK:

The display is as specified in the normal condition column.

Result

Proceed to

NG

A

OK (When troubleshooting according to Problem Symptoms Table)

B

OK (When troubleshooting according to the DTC)

C
B

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

C

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

A

2.

CHECK HARNESS AND CONNECTOR (SMOG VENTILATION SENSOR - IG POWER SOURCE AND BODY GROUND)

(a) Disconnect the A71 smog ventilation sensor connector.

(b) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection

Condition

Specified Condition

A71-3 (IG) - Body ground

Engine switch on (IG)

11 to 14 V

A71-3 (IG) - Body ground

Engine switch off

Below 1 V

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

A71-6 (E) - Body ground

Always

Below 1 Ω
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

3.

CHECK HARNESS AND CONNECTOR (SMOG VENTILATION SENSOR - AIR CONDITIONING AMPLIFIER ASSEMBLY)

(a) Disconnect the J42 air conditioning amplifier assembly connector.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

A71-1 (SG) - J42-2 (SG-2)

Always

Below 1 Ω

A71-2 (DGS) - J42-25 (DGS)

Always

Below 1 Ω

J42-2 (SG-2) or A71-1 (SG) - Body ground

Always

10 kΩ or higher

J42-25 (DGS) or A71-2 (DGS) - Body ground

Always

10 kΩ or higher
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

4.

INSPECT SMOG VENTILATION SENSOR

(a) Remove the smog ventilation sensor.

Click here

*a

Component without harness connected

(Smog Ventilation Sensor)

(b) Connect a positive (+) lead from the battery to terminal 3 (IG) and a negative (-) lead to terminal 6 (E).

(c) Allow exhaust gas (HC, CO) to travel to the sensing portion of the smog ventilation sensor, and measure the resistance between terminals 1 (SG) and 2 (DGS).

OK:

When the sensor is exposed to exhaust gas, the resistance increases.

HINT:

The resistance of the sensor before being exposed to exhaust gas is 10 kΩ to 40 kΩ.

OK

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY

NG

REPLACE SMOG VENTILATION SENSOR

    Evaporator Temperature Circuit (B1417/17)
    DESCRIPTION The No. 2 air conditioning harness assembly is installed on the evaporator in the rear air conditioner unit to detect the temperature of the cooled air that has passed through the evaporat ...

    Rear Room Temperature Sensor Circuit (B1419/19)
    DESCRIPTION The cooler (No. 2 room temp. sensor) thermistor is installed in the rear panel to detect the rear cabin temperature, which is used to control the air conditioning system. The resistance of ...

    Other materials:

    Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual > Smart Access System With Push-button Start (for Entry Function): Driver Side Door Entry Unlock Function does not Operate
    DESCRIPTION If the entry unlock function does not operate for the driver door only, but the entry lock function operates, the request code is being transmitted properly from the driver door. In this case, there may be a problem related to the unlock sensor (connection between the certification ECU ( ...

    Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual > Lighting System (w/ Automatic Headlight Beam Level Control System): Data List / Active Test
    DATA LIST / ACTIVE TEST DATA LIST NOTICE: In the table below, the values listed under "Normal Condition" are reference values. Do not depend solely on these reference values when deciding whether a part is faulty or not. HINT: Using the Techstream to read the Data List allows the values or states of ...

    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Owners Manual

    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Repair Manual

    © 2025 Copyright www.lexusrx.net
    0.0143