FI SYSTEM DIAGNOSIS 4-75
Step 4
HO2 sensor output voltage check
1) Connect the ECM coupler and HO2 sensor coupler.
2) Warm up the engine enough.
3) Insert the needle-point probes to the lead wire coupler.
4) Measure the HO2 sensor output voltage between the B wire
and B/Br wire, in idling condition.
09900-25008: Multi circuit tester set
09900-25009: Needle-point probe set
Tester knob indication: Voltage (
)
HO2 sensor output voltage at idle speed:
0.4 V or less
(
+
terminal: B –
-
terminal: B/Br)
5) If OK, lift and support the fuel tank (
5-2) and pinch the
PAIR hose
1
with a proper hose clamp.
6) Measure the HO2 sensor output voltage while holding the
engine speed at 5 000 r/min.
HO2 sensor output voltage at 5 000 r/min:
0.6 V or more
(
+
terminal: B –
-
terminal: B/Br)
Is check result OK?
4
4
YES
Replace the ECM with a known good one, and
inspect it again.
NO
Replace the HO2 sensor with a new one.
(
4-93)
4