Honda Civic Service Manual page 409

Primary Heated Oxygen Sensor {Primary HO2SI (Sensor 1)
t
('96 - 98 Models except Dl6Y5 engine with M/Tl
The Heated Oxygen Sensor (HO2S) detects the oxygen content in the exhaust gas and signals the ECM/PCM. In operation,
the ECM/PCM receives the sjgnals from the sensor and varies the duration during which fuel is injected To stabilize the
sensor,s output, the sensor has an internal heater. The Primary HO2S (Sensor 1) is installed in the exhaust manifold.
HO2S:
VOLTAGE {VI
The scan tool indicates Diagnostic Trouble Code (DTC) P0131; A low voltage
Oxygen Sensor (H02S) (Sensor 1) circuit.
R|cH-AIR-
- LEAN
FUEL
RANO
problem in the Primary Heated
SENSOR
ztRcoNlA
The MIL has be€n teported on.
DTC P0131 is siorcd.
Problom verificalion:
1. Do the ECM/PCM Reset Pro'
cedure.
2 . S t a r t t h e e n g i n e . H o l d t h e
engine at 3,000 rpm with no
load (in Park or neutral) until
the radiator fan comes on,
3. Test-drive with the A/T in E
position (M/T in 4th gear)
4 . C h e c k t h e P r i m a r y H O 2 S
(Sensor 1) output voltage with
the scan tool during accelera-
tion using wide open throttle.
lntcrmift€nt failura, 3Y3tem is OK
at this tims. Check for Poor con-
nections or loo3e wi.o3 at C123
(Primlry HO2S, 3sn3or 1) and
ECM/PCM,
(To page 1I-140)
{cont'd)
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