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DTC Troubleshooting

DTC TROUBLESHOOTING CHART

Step Action YES NO
1  Was "Engine and Emission Control System Check" performed?  Go to Step 2. Go to ENGINE AND EMISSION CONTROL SYSTEM CHECK .
2  Wire harness check 
  1. Turn ignition switch to OFF position.
  2. Check for proper terminal connection to EVAP leak check module and ECM connectors.
  3. If connections are OK, recheck DTC.

Is DTC P1420 or P1421 detected again? 		 Go to Step 3. Intermittent trouble.
3  Wire harness check 
  1. Check EVAP vent valve circuit referring to DTC P0449: EVAPORATIVE EMISSION SYSTEM VENT VALVE CIRCUIT .

Are they in good condition? 		 Go to Step 4. Repair or Replace defective wire harness.
4  EVAP vent valve check 
  1. Check EVAP vent valve for performance referring "EVAP Vent Valve Check" under EVAP LEAK CHECK MODULE INSPECTION .

Is it in good condition? 		 Substitute a known-good ECM and recheck. Replace EVAP leak check module.
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