LEMON Manuals: Even more car manuals for everyone
Home >> Nissan-Datsun >> 2003 >> Sentra Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 204 (Engine Controls - Self-Diagnostics - 1.8L - Ca) >> Diagnostic Tests >> DTC P0420: 3-Way Catalyst Function >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Nissan Sentra. However, it is still accessible from the selected car via links, so may be relevant.
  1. Inspect exhaust system for damage. If problem exists, repair as necessary and retest system. If problem does not exist, go to next step.
  2. Start engine and run at idle. Check for exhaust leak in front of 3-way catalyst. Check intake system for leaks. If problem exists, repair or replace faulty components as necessary and retest system. If problem does not exist, go to next step.
  3. Check ignition timing. See ON-VEHICLE ADJUSTMENTS article. If ignition timing is incorrect, adjust as necessary and retest system. If ignition timing is okay, go to next step.
  4. Turn engine off and turn ignition on. Using a DVOM, backprobe PCM harness connector and measure voltage between ground and terminals No. 101 (Red/Black wire), No. 103 (Yellow/Black wire), No. 105 (Green/Black wire) and No. 107 (Blue/Black wire) at PCM harness connector. See Figure . If battery voltage exists, go to next step. If battery voltage does not exist, repair appropriate injector or circuit as necessary and retest system. See SYSTEM & COMPONENT TESTING article.
  5. Check for spark at misfiring cylinder(s). If spark is detected, go to next step. If no spark is detected, go to DTC P0350: IGNITION SIGNAL  .
    6. NOTE: NEW "O" rings must be used on all fuel injectors once removed.
  6. Turn ignition off and allow engine to cool. Ensure no fire hazards exist and remove fuel injector assembly with fuel lines and harness connectors connected. Place a suitable cup under each fuel injector to collect fuel. Disconnect all ignition coil harness connectors. Turn ignition on. Verify fuel is not dripping from fuel injectors. If any injector is dripping, replace fuel injectors which are leaking. If no fuel injectors are leaking, go to next step.
  7. No problem is indicated at this time. Problem may be intermittent. See TESTING PROCEDURE  under SELF-DIAGNOSTIC SYSTEM. If DTC still exists, replace 3-way catalyst.
scientia non olet · About LEMON Manuals