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Home >> Infiniti >> 2001 >> G20 Base, Automatic, RE4F03W >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0420: 3-Way Catalyst Function >> Procedure
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DTC P0420: 3-Way Catalyst Function: Procedure

  1. Inspect exhaust system for damage and repair as necessary. Start engine and let it idle. Check for exhaust leaks before 3-way catalyst. Check for intake air leaks after MAF sensor. Repair as necessary and retest system. If no problems are found, go to next step.
    2. CAUTION: DO NOT use ECM ground terminals when measuring voltage.
  2. Check ignition timing. See ON-VEHICLE ADJUSTMENTS article. Adjust, if necessary and retest system. If ignition timing is okay, turn engine off and turn ignition on. Measure voltage between ground and ECM terminals No. 101, 103, 105 and 107 by backprobing. See Figure and Figure . If battery voltage exists, go to next step. If battery voltage does not exist, repair appropriate injector or circuit. See FUEL SYSTEM in SYSTEM & COMPONENT TESTING article.
  3. Disconnect ignition wires from spark plugs individually and connect a known good spark plug to wire. Place spark plug on good ground. Crank engine and check for spark. If spark exists at every plug wire, go to next step. If spark does not exist every plug wire, repair ignition system as necessary. See IGNITION SYSTEM in SYSTEM & COMPONENT TESTING article.
  4. Turn ignition off. Remove injector assembly. Keep all associated fuel lines connected. Disconnect 6-pin distributor harness connector. Turn ignition on. Verify fuel is not dripping from injectors. Replace injectors which are leaking. If no injectors are leaking, go to next step.
  5. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
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