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Home >> Suzuki >> 2007 >> SX4 Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine General Information And Diagnosis >> Diagnostic Information and Procedures >> DTC P0420: Catalyst System Efficiency Below Threshold (Bank-1) >> DTC Troubleshooting
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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  Exhaust system visual inspection 
  1. Check exhaust system for leaks, damage and loose.

Is it in good condition? 		 Go to Step 3. Repair or replace.
3  HO2S circuit check 
  1. Check signal and ground circuits of HO2S for high resistance referring to step 3 of DTC P0137 / P0138: O2 SENSOR CIRCUIT LOW VOLTAGE / HIGH VOLTAGE (SENSOR-2, BANK-1) (EVAP LEAK CHECK MODEL) .

Are they in good condition? 		 Go to Step 4. Repair or replace.
4 
  1. Replace exhaust manifold (built in warm up three way catalytic converter) and exhaust center pipe (built in three way catalytic converter).
  2. Perform DTC CONFIRMATION PROCEDURE .

Is DTC P0420 still detected? 		 Substitute a known-good ECM and recheck. End.
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