Cars Technical Articles - Diagnostic Tip for Malfunction Indicator Light (MIL) Illuminated, DTC P0420 and P0430 Set

Diagnostic Tip for Malfunction Indicator Light (MIL) Illuminated, DTC P0420 and P0430 Set

- Edited: Sep 09, 2022
- Popularity: 25 Views

Makes:

GMC

Vehicles Affected:

  • 2016-2018 Cadillac CTS
  • 2015-2018 Cadillac Escalade
  • 2016-2018 Chevrolet Camaro
  • 2014-2018 Chevrolet Corvette
  • 2014-2018 Chevrolet Silverado
  • 2015-2018 Chevrolet Suburban
  • 2015-2018 Chevrolet Tahoe
  • 2014-2018 GMC Sierra
  • 2015-2018 GMC Yukon

Condition:

Some customers may comment that the Malfunction Indicator Light (MIL) is illuminated and DTC P0420 and P0430 are set.

Cause:

This may be caused by excessive sand and/or debris entering the air filter box and bypassing the seal of
the air filter, due to not properly sealing, causing damage to the HO2 sensor element and the catalytic
converter to become blocked with sand and debris particles.

Correction:

Do not replace any of the parts until the air filter housing has been validated to be completely sealed.
If the condition is evident, an inspection of the air box and air filter seal must be done.
Follow the Service Procedure steps in order to verify the sealing of the air filter to the housing surface.
After validating the air box has been sealed, repair the P0420 and the P0430 codes as needed

Service Procedure:

Catalytic Converter with sand:

Diagnostic Tip DTC P0420 P0430

HO2 Sensor with sand:
Diagnostic Tip DTC P0420 P0430

1. Inspect all the air housing cover for any missing tabs and/or fasteners (1).
2. Remove the air filter housing cover and inspect the seal around the air filter (2).

Diagnostic Tip DTC P0420 P0430


3. Inspect the air filter sealing surface for signs of not contacting the air filter seal (1, 2).
4. Inspect the air filter housing cover for dirt and/or debris bypassing the air filter (3).

Diagnostic Tip DTC P0420 P0430


5. Inspect the air cleaner outlet duct for any dirt and/or debris.
• If dirt and debris has been found bypassing the air filter due to a faulty seal, replace the air filter, as necessary.
• If the air filter housing has been found not properly sealing, replace the Air Cleaner Assembly,