Diagnostic trouble code (DTC) information

Condition 

Diagnostic trouble code (DTC) ECM-3502 is stored if the control module registers that the engine misfires to such an extent that exhaust emissions increase (the extent varies with load and engine speed (RPM)).

Substitute Value 

• three-way catalytic converter (TWC) diagnosis shut off
• leakage diagnosis shut off
• rear heated oxygen sensor control shut off

Possible Source 

• repeated cold starting where the engine coolant temperature (ECT) has not reached normal operating temperature between starts.
• water in spark plug wells
• defective spark plugs
• contaminated or faulty fuel
• fuel stoppage
• air leakage
• Blocked crankcase ventilation.
• Damaged VVT-unit.
• blocked/leaking injectors
• faulty fuel pressure
• uneven compression

Fault symptom[s] 

• engine misfires
• engine difficult to start
• poor performance
• uneven idle
• engine not firing on all cylinders