P0143

DTC P0143 OXYGEN SENSOR CIRCUIT LOW VOLTAGE (BANK 1 SENSOR 3)

HINT: This DTC has been added to meet the requirement for Partial Zero Emission Vehicle (PZEV).

CIRCUIT DESCRIPTION

DTC Detection Condition:

Monitor Strategy:

Typical Enabling Conditions:

Typical Malfunction Thresholds:

Component Operating Range:

This sensor (heated oxygen sensor 3) is similar to the heated oxygen sensor 2, only difference between the two sensors is that this is not used to regulate the air-fuel ratio. The sensor is located after the rear catalyst (hydrocarbon (HC) absorptive catalyst) only to detect the deterioration in the catalyst.

In a circuit inside the ECM, impedance* of the heated oxygen sensor 3 is measured by the ECM. The ECM determines that there is a malfunction in the sensor when the measured impedance deviates from the standard range.

*: The effective resistance in an alternating current electrical circuit.

P0143
During normal feedback control of the air-fuel ratio, there are still small variations in the exhaust gas oxygen concentration. As a result, the ECM cannot detect a malfunction in the heated oxygen sensor 3 using the conventional method of sensing output voltage variation. In a circuit inside the ECM, the impedance* of the sensor 3 is measured by the ECM. The ECM determines that there is a malfunction in the sensor when the measured impedance deviates from the standard range.

*: The effective resistance in an alternating current electrical circuit.

HINT: The impedance cannot be measured with an ohm meter.

HINT: P0142 and P0143
- P0142 indicates deterioration of the heated oxygen sensor 3 by the ECM calculating the impedance of the sensor 3 after the typical enabling conditions are satisfied (detected after 2 driving-cycles).
- P0143 indicates an open or short circuit in the heated oxygen sensor 3 system. (1 driving-cycle). The ECM determines this by sensing that the impedance of the sensor exceeds the threshold, i.e. less than 5 Ohms or more than 5,000 Ohms.

Wiring Diagram:

CONFIRMATION ENGINE RACING PATTERN for DTC P0143

PURPOSE






HINT: Performing this confirmation pattern will activate the DTC detection (P0143) of the ECM. This is very useful for verifying the completion of a repair.

a. Clear the DTCs.
1. Disconnect the battery cable or remove the EFI and ETCS fuses for 60 seconds or more.

b. Start the engine and warm it up with all the accessory switches OFF.
c. Run the engine at 2,000 to 3,000 rpm for about 5 minutes.
d. Read the DTC.

NOTE: If the conditions in this test are not strictly followed, detection of a malfunction will not occur.

Step 1 - 2:

Step 3:

INSPECTION PROCEDURE

HINT: Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.