Nissan Sentra. Manual — part 397
EC-284
< DTC/CIRCUIT DIAGNOSIS >
[MRA8DE]
P0420 THREE WAY CATALYST FUNCTION
11. Rev engine up to 2,000 to 3,000 rpm and hold it for 3 consecutive minutes then release the accelerator
pedal completely.
12. Check the indication of “CATALYST”.
Which is displayed on CONSULT screen?
CMPLT >> GO TO 5.
INCMP >> GO TO 3.
3.
PERFORM DTC CONFIRMATION PROCEDURE-2
1. Wait 5 seconds at idle.
2. Rev engine up to 2,000 to 3,000 rpm and maintain it until “INCMP” of “CATALYST” changes to “CMPLT” (It
will take approximately 5 minutes).
Does the indication change to “CMPLT”?
YES
>> GO TO 5.
NO
>> GO TO 4.
4.
PERFORM DTC CONFIRMATION PROCEDURE AGAIN
1. Stop engine and cool it down to less than 70
°C (158°F).
2. Perform DTC confirmation procedure again.
>> GO TO 2.
5.
PERFORM DTC CONFIRMATION PROCEDURE-3
Check 1st trip DTC.
Is 1st trip DTC detected?
YES
>> Proceed to
.
NO
>> INSPECTION END
6.
PERFORM COMPONENT FUNCTION CHECK
Perform component function check. Refer to
EC-284, "Component Function Check"
NOTE:
Use component function check to check the overall function of the three way catalyst (manifold). During this
check, a 1st trip DTC might not be confirmed.
Is the inspection result normal?
YES
>> INSPECTION END
NO
>> Proceed to
.
Component Function Check
INFOID:0000000009758531
1.
PERFORM COMPONENT FUNCTION CHECK
Without CONSULT
1. Start engine and warm it up to the normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Restart engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no
load.
4. Let engine idle for 1 minute.
5. Open engine hood.
6. Check the voltage between ECM harness connector terminals as per the following condition.
Is the inspection result normal?
ECM
Condition
Voltage (V)
Connector
+
–
Terminal
F24
22
23
Keeping engine speed at
2500 rpm constant under no
load
The voltage fluctuation cy-
cle takes more than 5 sec-
onds.
• 1 cycle: 0.6 - 1.0
→ 0 - 0.3
→ 0.6 - 1.0
P0420 THREE WAY CATALYST FUNCTION
EC-285
< DTC/CIRCUIT DIAGNOSIS >
[MRA8DE]
C
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EC
N
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YES
>> INSPECTION END
NO
>> Proceed to
.
Diagnosis Procedure
INFOID:0000000009758532
1.
CHECK EXHAUST SYSTEM
Visually check exhaust tubes and muffler for dent.
Is the inspection result normal?
YES
>> GO TO 2.
NO
>> Repair or replace error-detected parts.
2.
CHECK EXHAUST GAS LEAK
1. Start engine and run it at idle.
2. Listen for an exhaust gas leak before the three way catalyst (manifold).
Is exhaust gas leak detected?
YES
>> Repair or replace error-detected parts.
NO
>> GO TO 3.
3.
CHECK INTAKE AIR LEAK
Listen for an intake air leak after the mass air flow sensor.
Is intake air leak detected?
YES
>> Repair or replace error-detected parts.
NO
>> GO TO 4.
4.
CHECK IGNITION TIMING AND IDLE SPEED
Check the following items.
• Ignition timing (Refer to
.)
• Idle speed (Refer to
Is the inspection result normal?
YES
>> GO TO 5.
NO
>> Perform “BASIC INSPECTION”. Refer to
5.
CHECK FUEL INJECTOR
Check the fuel injector. Refer to
EC-450, "Component Function Check"
.
Is the inspection result normal?
YES
>> GO TO 6.
NO
>> Perform
.
6.
CHECK FUNCTION OF IGNITION COIL-1
CAUTION:
Do the following procedure in the place where ventilation is good without the combustible.
1. Turn ignition switch OFF.
2. Remove fuel pump fuse in IPDM E/R to release fuel pressure.
NOTE:
Do not use CONSULT to release fuel pressure, or fuel pressure applies again during the following proce-
dure.
3. Start engine.
4. After engine stalls, crank it two or three times to release all fuel pressure.
PBIB1216E
EC-286
< DTC/CIRCUIT DIAGNOSIS >
[MRA8DE]
P0420 THREE WAY CATALYST FUNCTION
5. Turn ignition switch OFF.
6. Remove all ignition coil harness connectors to avoid the electrical discharge from the ignition coils.
7. Remove ignition coil and spark plug of the cylinder to be checked.
8. Crank engine for 5 seconds or more to remove combustion gas in the cylinder.
9. Connect spark plug and harness connector to ignition coil.
10. Fix ignition coil using a rope etc. with gap of 13 - 17 mm (0.52 -
0.66 in) between the edge of the spark plug and grounded metal
portion as shown in the figure.
11. Crank engine for about 3 seconds, and check whether spark is
generated between the spark plug and the grounded metal por-
tion.
CAUTION:
• Do not approach to the spark plug and the ignition coil
within 50 cm (19.7 in). Be careful not to get an electrical
shock while checking, because the electrical discharge
voltage becomes 20 kV or more.
• It might cause to damage the ignition coil if the gap of more than 17 mm (0.66 in) is taken.
NOTE:
When the gap is less than 13 mm (0.52 in), the spark might be generated even if the coil is mal-
functioning.
Is the inspection result normal?
YES
>> GO TO 10.
NO
>> GO TO 7.
7.
CHECK FUNCTION OF IGNITION COIL-2
1. Turn ignition switch OFF.
2. Disconnect spark plug and connect a known-good spark plug.
3. Crank engine for about 3 seconds, and recheck whether spark is generated between the spark plug and
the grounded metal portion.
Is the inspection result normal?
YES
>> GO TO 8.
NO
>> Check ignition coil, power transistor and their circuits. Refer to
.
8.
CHECK SPARK PLUG
Check the initial spark plug for fouling, etc. Refer to
.
Is the inspection result normal?
YES
>> Replace spark plug(s) with standard type one(s). For
spark plug type, refer to
NO
>> 1. Repair or clean spark plug. Refer to
2. GO TO 9.
9.
CHECK FUNCTION OF IGNITION COIL-3
1. Reconnect the initial spark plugs.
2. Crank engine for about 3 seconds, and recheck whether spark is generated between the spark plug and
the grounded portion.
Is the inspection result normal?
YES
>> INSPECTION END
Spark should be generated.
JMBIA0066GB
Spark should be generated.
SEF156I
Spark should be generated.
P0420 THREE WAY CATALYST FUNCTION
EC-287
< DTC/CIRCUIT DIAGNOSIS >
[MRA8DE]
C
D
E
F
G
H
I
J
K
L
M
A
EC
N
P
O
NO
>> Replace spark plug(s) with standard type one(s). For spark plug type, refer to
.
10.
CHECK FUEL INJECTOR
1. Turn ignition switch OFF.
2. Remove fuel injector assembly. Refer to
EM-40, "Removal and Installation"
.
Keep fuel hose and all fuel injectors connected to fuel tube.
3. Disconnect all ignition coil harness connectors.
4. Reconnect all fuel injector harness connectors disconnected.
5. Turn ignition switch ON.
Does fuel drip from fuel injector?
YES
>> GO TO 11.
NO
>> Replace the fuel injector(s) from which fuel is dripping. Refer to
.
11.
CHECK INTERMITTENT INCIDENT
Check intermittent incident. Refer to
GI-39, "Intermittent Incident"
.
Is the trouble fixed?
YES
>> INSPECTION END
NO
>> Replace three way catalyst assembly. Refer to
.
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