Toyota Corolla (E120) 2002–2008 Repair Manual / Diagnostics / Sfi system / Oxygen sensor heater control
circuit... / Inspection procedure
Toyota Corolla (E120): Inspection procedure
Hint
:
- if different dtcs related to different systems that have terminal e2 as the ground terminal are output simultaneously, terminal e2 may be open.
- 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.
1 Inspect heated oxygen sensor(heater resistance)
- Disconnect the h5 or h8 heated oxygen sensor connector.
- measure the resistance between the terminals of the heated oxygen sensor connector.

Standard:

- Reconnect the heated oxygen sensor connector.


2 Inspect efi relay
- Remove the efi relay from the engine room r/b.
- check for continuity in the efi relay.

Standard:

- Reinstall the efi relay.


3 Inspect ecm(ht1a or ht1b voltage)
- Turn the ignition switch on.
- measure the voltage between the applicable terminals of the e4 and e5 ecm connectors.

Standard:



4 Check harness and connector(heated oxygen sensor – ecm, heated oxygen sensor – efi relay)
- Check the harness and connector between the ecm and heated oxygen sensor connectors.
- Disconnect the h5 or h8 heated oxygen sensor connector.
- Disconnect the e4 or e5 ecm connector.
- Check the resistance between the wire harness side connectors.

Standard (check for open):

Standard (check for short):


- Reconnect the heated oxygen sensor connector.
- Reconnect the ecm connector.
- check the harness and connector between the heated oxygen sensor connector and efi relay.
- Disconnect the h5 or h8 heated oxygen sensor connector.
- Remove the efi relay from the engine room r/b.
- Check the resistance between the wire harness side connectors.

Standard (check for open):

Standard (check for short):

- Reconnect the heated oxygen sensor connector.
- Reinstall the efi relay.


Replace ecm
Other materials:
Replacement
Hint: components:
1. Precaution
2. Disconnect battery negative terminal
3. Remove parking brake hole cover sub–assy
4. Remove floor shift shift lever knob sub–assy (m/t transaxle)
5. Remove shifting hole cover sub–assy (m/t transaxle)
6. Remove console panel upper
7. Remove conso ...
How to proceed with troubleshooting
The hand–held tester can be used at step 4, 6, 8 and 9.
1 Vehicle brought to workshop
2 Customer problem analysis
3 Warning light check
4 The dtcs check (present and past dtcs)
5 The dtcs chart
6 Circuit inspection
7 Repair
8 Clear the dtcs (present and past dtcs)
9 The dt ...
Washer fluid
Add washer fluid in the following situations:
● A washer does not work.
● Vehicles without a multi-information display: The low windshield washer fluid
warning light (if equipped) comes on.
● Vehicles with a multi-information display: The warning message (if equipped) appear ...


