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Home >> Suzuki >> 2012 >> Equator Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine General Information & Diagnosis - Qr25DE (3 Of 5) >> DTC P0420: Three Way Catalyst Function >> Diagnosis Procedure
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Diagnosis Procedure

DIAGNOSIS PROCEDURE CHART

Step Action YES NO
1  CHECK EXHAUST SYSTEM 
Visually check exhaust tubes and muffler for dents.
OK or NG 		 GO TO 2. Repair or replace.
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).
G00538119Courtesy of SUZUKI OF AMERICA CORP.

OK or NG 		 GO TO 3. Repair or replace.
3  CHECK INTAKE AIR LEAK 
Listen for an intake air leak after the mass air flow sensor.
OK or NG 		 GO TO 4. Repair or replace.
4  CHECK IGNITION TIMING 
Check the following items. Refer to [BASIC INSPECTION ].
G00538120Courtesy of SUZUKI OF AMERICA CORP.

OK or NG 		 GO TO 5. Follow the [BASIC INSPECTION ].
5  CHECK FUEL INJECTOR 
  1. Stop engine and then turn ignition switch ON.
  2. Check voltage between ECM terminals 22, 23, 41, 42 and ground with SDT or tester.
G06444168Courtesy of SUZUKI OF AMERICA CORP.

Voltage: Battery voltage 
OK or NG 		 GO TO 6. Perform [FUEL INJECTOR CIRCUIT CHECK ].
6  CHECK FUNCTION OF IGNITION COIL-I 
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.
G06444169G06444170Courtesy of SUZUKI OF AMERICA CORP.SUZUKI OF AMERICA CORP.
NOTE: Do not use SDT to release fuel pressure, or fuel pressure applies again during the following procedure.

  1. 3. Start engine.
  2. 4. After engine stalls, crank it two or three times to release all fuel pressure.
  3. 5. Turn ignition switch OFF.
  4. 6. Remove all ignition coil harness connectors to avoid the electrical discharge from the ignition coils.
  5. 7. Remove ignition coil and spark plug of the cylinder to be checked.
  6. 8. Crank engine for 5 seconds or more to remove combustion gas in the cylinder.
  7. 9. Connect spark plug and harness connector to ignition coil.
  8. 10. Fix ignition coil using a rope etc. with gap of 13 - 17 mm between the edge of the spark plug and grounded metal portion as shown in the figure.
G06444169G06444170Courtesy of SUZUKI OF AMERICA CORP.SUZUKI OF AMERICA CORP.

  1. 11. Crank engine for about three seconds, and check whether spark is generated between the spark plug and the grounded metal portion.

    Spark should be generated. 

    CAUTION:
    • Never approach to the spark plug and the ignition coil within 50 cm. Be careful not to get an electrical shock while checking, because the electrical discharge voltage becomes 20kV or more.
    • It might cause to damage the ignition coil if the gap of more than 17 mm is taken.
    NOTE: When the gap is less than 13 mm, the spark might be generated even if the coil is malfunctioning.

OK or NG 		 GO TO 10. GO TO 7.
7  CHECK FUNCTION OF IGNITION COIL-II 
  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.

    Spark should be generated. 


OK or NG 		 GO TO 8. Check ignition coil, power transistor and their circuits. Refer to Ignition Signal Circuit Check .
8  CHECK SPARK PLUG 
Check the initial spark plug for fouling, etc. Refer to [IGNITION COIL: REMOVAL AND INSTALLATION ].
G00538115Courtesy of SUZUKI OF AMERICA CORP.

OK or NG 		 Replace spark plug(s) with standard type one(s).
  1. Repair or clean spark plug.
  2. GO TO 9.
9  CHECK FUNCTION OF IGNITION COIL-III 
  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.

    Spark should be generated. 


OK or NG 		 INSPECTION END  Replace spark plug(s) with standard type one(s). For spark plug type. Refer to IGNITION COIL: REMOVAL AND INSTALLATION .
10  CHECK FUEL INJECTOR 
  1. Turn ignition switch OFF.
  2. Remove fuel injector assembly. Refer to [FUEL INJECTOR AND FUEL TUBE: REMOVAL AND INSTALLATION [QR25DE] ]

    Keep fuel hose and all fuel injectors connected to fuel injector gallery.

  3. Reconnect all fuel injector harness connectors.
  4. Disconnect all ignition coil harness connectors.
  5. Turn ignition switch ON. check that fuel does not drip from fuel injector.

OK or NG 		 GO TO 11. Replace the fuel injector (s) from which fuel is dripping. Refer to FUEL INJECTOR AND FUEL TUBE: REMOVAL AND INSTALLATION [QR25DE] .
11  CHECK INTERMITTENT INCIDENT 
Perform [SERVICE INFORMATION FOR ELECTRICAL INCIDENT: INTERMITTENT INCIDENT ]		 INSPECTION END  Replace three way catalyst (manifold). Refer to EXHAUST MANIFOLD AND THREE WAY CATALYST: EXPLODED VIEW [QR25DE] .
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