P0420 KIA - Warm Up Catalyst Efficiency Below Threshold Bank 1

Repair Importance Level: 2/3
Repair Difficulty Level: 2/3  What does this mean?

P0420 KIA Possible Causes

  • Faulty Three-way Catalyst Converter Bank 1
  • Exhaust Tube
  • Intake Air Leaks
  • Faulty Oxygen (O2) Sensor
  • Faulty Fuel injector(s)
  • Leaking Fuel Injector (s)
  • Faulty Spark plugs
  • Improper Ignition Timing
  • Faulty Engine Control Module (ECM)
  • Dirty Air Filter

First diagnose P0420 KIA code

    Check the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded terminals.

P0420 KIA Tech Notes

As the code description implies the P0420 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0420 code is combined with other codes, try fixing the other codes first.

Cost of diagnosing the P0420 KIA code

    Labor: 1.0

    The cost of diagnosing the P0420 KIA code is 1.0 hour of labor. The auto repair labor rates vary widely across the country, and even within the same city. Most auto repairs shops charge between $75 and $150 per hour.

When is the P0420 KIA code detected?

- Three way catalytic converter Bank 1 does not operate properly.
- Three way catalyst converter Bank 1 does not have enough oxygen storage capacity.

P0420 KIA Possible Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)

P0420 KIA Meaning

The catalyst’s efficiency is demonstrated by its ability to oxidize CO and hydrocarbon emissions. The Powertrain Control Module (PCM) compares the output signals of the front and rear oxygen sensors to determine whether the output of the rear sensor is beginning to match the output of the front oxygen sensor. Air/fuel mixture compensation keeps the frequency of the front oxygen sensor high due to the changes from rich-to-lean comvustio. The catalyst causes the rear oxygen sensor to have a lower frequency. As the catalyst wears, the rear oxygen sensor’s signal trace begins to match the front oxygen sensor’s signal trace. That is because the catalyst becomes saturated with oxygen and cannot use the oxygen to convert hydrocarbon and CO into H₂O and CO₂ with the same efficiency as when it was new. A completely worn catalyst shows a 100% match between the frequency of the front and rear sensors.
OBDII Code P0420 KIA - Warm Up Catalyst Efficiency Below Threshold Bank 1 - Engine-Codes.com

P0420 KIA More Information

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