P1271

DTC P1271 A/F SENSOR 1

Component Description




The air fuel ratio (A/F) sensor 1 is a planar dual-cell limit current sensor. The sensor element of the A/F sensor 1 is the combination of a Nernst concentration cell (sensor cell) with an oxygen-pump cell,
which transports ions. It has a heater in the element.

The sensor is capable of precise measurement Lambda = 1, but also in the lean and rich range. Together with its control electronics, the sensor outputs a clear, continuous signal throughout a wide range (0.7 < Lambda < air).

The exhaust gas components diffuse through the diffusion gap at the electrode of the oxygen pump and Nernst concentration cell, where they are brought to thermodynamic balance.




An electronic circuit controls the pump current through the oxygen pump cell so that the composition of the exhaust gas in the diffusion gap remains constant Lambda at = 1. Therefore, the A/F sensor 1 is able to indicate air/fuel ratio by this pumping of current. In addition, a heater is integrated in the sensor to ensure the required operating temperature of 700 - 800 °C (1,292 - 1,472 °F).

CONSULT-II Reference Value In Data Monitor Mode:

CONSULT-II Reference Value in Data Monitor Mode

On Board Diagnosis Logic:

On Board Diagnosis Logic

DTC Confirmation Procedure

NOTE: If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at least 10 seconds before conducting the next test.

TESTING CONDITION: Before performing the following procedure, confirm that battery voltage is more than 10.5 V at idle.

WITH CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select "A/F SEN1 (B1)" or "A/F SEN1 (B2)" in "DATA MONITOR" mode with CONSULT-II.




3. Check "A/F SEN1 (B1)" or "A/F SEN1 (B2)" indication.
If the indication is constantly approx. 0 V, go to "Diagnostic Procedure" below.
If the indication is not constantly approx. 0 V, go to next step.

4. Turn ignition switch OFF, wait at least 10 seconds and then restart engine.
5. Drive and accelerate vehicle to more than 40 km/h (25 MPH) within 20 seconds after restarting engine.




6. Maintain the given conditions for about 20 consecutive seconds.

NOTE:
- Keep the accelerator pedal as steady as possible during the cruising.
- If this procedure is not completed within 1 minute after restarting engine at step 4, return to step 4.

7. If 1st trip DTC is displayed, go to "Diagnostic Procedure" below.

WITH GST
Follow the procedure "WITH CONSULT-II" above.

Wiring Diagram

EC-AF1B1-01:

EC-AF1B2-01:

Diagnostic Procedure

Diagnostic Procedure (Step 1):

Diagnostic Procedure (Steps 2 - 3):

Diagnostic Procedure (Steps 4 - 5):