Federal
TROUBLESHOOTING HINTSHint 1:
The exhaust gas purification performance will worsen it there is a malfunction of the heated oxygen sensor.
Hint 2:
If the heated oxygen sensor output voltage is outside the standard value even though the results of the checking of the heated oxygen sensor are normal, the cause is probably a malfunction of a component related to mixture control.
[Examples]:
(1) Malfunction of injector.
(2) Air is drawn into the intake manifold from a leaking gasket, etc.
(3) Malfunction of volume air flow sensor, intake air temperature sensor, barometric pressure sensor or engine coolant temperature sensor.
INSPECTION:
Using Scan Tool
HARNESS INSPECTION:
STEP 1. Check for continuity between the heated oxygen sensor and the MFI relay.
- MFI relay connector: Disconnected
- Heated oxygen sensor connector: Disconnected
- Touch the ohmmeter probes to both ends of the harness.
OK: GO TO STEP 2
NG: Repair the harness. (A1 - C1, B1 - C1)
STEP 2. Check for an open circuit or a short-circuit to ground between the heated oxygen sensor and the engine control module.
- Heated oxygen sensor connector: Disconnected
- Engine control module connector: Disconnected
OK: GO TO STEP 3
NG: Repair the harness. (A4 - 71, B4 - 73)
STEP 3. Check for an open circuit or a short-circuit to ground between the heated oxygen sensor and the engine control module.
- Heated oxygen sensor connector: Disconnected
- Engine control module connector: Disconnected
OK: GO TO STEP 4
NG: Repair the harness. (A3 - 3, B3 - 26)
STEP 4. Check for continuity in the ground circuit.
- Heated oxygen sensor connector: Disconnected
- Engine control module connector: Disconnected
OK: STOP
NG: Repair the harness. (A2 - 49, B2 - 49)
HEATED OXYGEN SENSOR CHECK
(1) Disconnect the connector to the heated oxygen sensor, then use the special tool (test harness) to make connections with the connection on the heated oxygen sensor side.
(2) Check that there is continuity between terminal (1) (red clip of the special tool) and terminal (3) (blue clip) of the heated oxygen sensor connector approx. 11 - 18 Ohms at a temperature of 20°C (68°F)].
(3) If there is no continuity, replace the heated oxygen sensor.
(4) Warm up the engine until the coolant temperature is 80°C (176°F) or higher.
(5) Using jumper wires, connect terminal (1) (red clip of the special tool) and terminal (3) (blue clip) of the heated oxygen sensor with the positive battery terminal and negative battery terminal respectively.
CAUTION: When connecting the jumper wires, be careful not to connect them to the wrong terminals, since this could damage the heated oxygen sensor
(6) Connect a digital voltmeter to terminal (2) (black clip of the special tool) and terminal (4) (white clip).
(7) While repeatedly racing the engine, measure the heated oxygen sensor's output voltage.
Standard value
(8) If the measurements are not as specified, the cause is probably a malfunction of the heated oxygen sensor.
NOTE: For removal and installation of the heated oxygen sensor, refer to Service and Repair.
(1) Disconnect the connector to the heated oxygen sensor, then use the special tool (test harness) to make connections with the connection on the heated oxygen sensor side.
(2) Check that there is continuity between terminal (1) (red clip of the special tool) and terminal (3) (blue clip) of the heated oxygen sensor connector [approx. 11 - 18 Ohms at a temperature of 20°C (68°F)].
(3) If there is no continuity, replace heated oxygen sensor.
NOTE:
1. If the scan tool dose not display the standard value although no abnormality is found by the above mentioned continuity test and harness check, replace the heated oxygen sensor.
2. For removal and installation of the oxygen sensor, refer to Service and Repair.