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Home >> Kia >> 2021 >> Niro Plug-In Hybrid EX >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Diagnosis (PHEV) (3 Of 6) >> DTC P0420-00: Catalyst System Efficiency Below Threshold (Bank 1) >> DTC Information >> DTC Detecting Condition
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DTC Information: DTC Detecting Condition

Item Detecting Condition Possible Cause
DTC Strategy
  • Check catalyst oxygen storage capacity
  • Exhaust system
  • S2
  • Catalyst converter
  • Out of range ECT sensor
  • Exhaust manifold
  • High fuel pressure
  • Incorrect connection
  • Misfire
  • Injector
  • EGR system
Enable Condition
  • Catalyst temperature (model) is between 550 and 930°C (1022 to 1706°F)
  • Engine coolant temperature is greater than 55°C (131°F)
  • Engine speed is between 1300 to 3000rpm
  • Vehicle speed is greater than 10.8km/h (3mph)
  • Engine load is between 29 and 81%
  • Barometric pressure is greater than 75kPa
  • Canister load is less than 0.5
  • No opening or closing of canister purge valve
  • Normal auxiliary battery voltage (11 to 16V)
  • Fuel trim active and lambda set point value is 1
  • Oxygen sensor element resistance is less than 1kΩ
  • Stable driving condition
  • When the difference between the actual engine speed and the filtered engine speed is less than 320rpm
  • When the difference between the actual intake air and the filtered intake air is less than 0.16g/rev
  • When the difference between the actual lambda value and the filtered lambda value is less than 7%
Threshold Value
  • Average malfunction index is less than 1
Diagnostic Time
  • 25 fuel trim controller cycles
MIL ON Condition
  • 2 driving cycles