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2016 Cadillac CTS-V: Service Bulletin: Diagnostic Tip for Malfunction Indicator Light (MIL)


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Nov 3, 2011
New Hampshire
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#16-NA-111: Diagnostic Tip for Malfunction Indicator Light (MIL) Illuminated, DTC P0420 and P0430 Set - (Jun 8, 2016)

Subject:*Diagnostic Tip for Malfunction Indicator Light (MIL) Illuminated, DTC P0420 and P0430 Set
Attention:*This Bulletin also applies to any of the models that may be Export from North America vehicles.


Brand: Model: Model Year: VIN: Engine: Transmission:
from to from to
CadillacCTS20162016LT1, LT4
Escalade20152016L83, L86
Escalade ESV20152016
ChevroletCamaro20162016LT1, LT4
Silverado20142016L83, L86, LV1, LV3
GMCSierra20142016L83, L86, LV1, LV3
Yukon20152016L83, L86
Yukon Denali20152016
Yukon XL20152016
Yukon XL Denali20152016


ConditionSome customers may comment that the Malfunction Indicator Light (MIL) is illuminated.

Technician may find DTC PO420 and P0430 set.


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 (3) and the catalytic converter to become blocked with sand and debris particles (1, 2).


Do not replace any of the parts until the air filter housing has been validated to be completely sealed.

If the condition is evident, 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 housing surface.

After validating the air box has been sealed, repair the P0420 and the P0430 codes as needed.
</dd></dl> <dl>
<dt>Service Procedure</dt>

  1. attachment.php
  2. Inspect the all the air housing cover for any missing tabs and/or fasteners (1).
  3. Remove the air filter housing cover and inspect the seal around the air filter (2).
  4. Inspect the air filter sealing surface for signs of not contacting the air filter seal (1, 2).
  5. Inspect the air filter housing cover for dirt and/or debris bypassing the air filter (3).
  6. 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, refer to the Air Cleaner Assembly Replacement in SI.
</dd></dl> <dl>
<dt>Warranty Information
</dt> <dd>
For vehicles repaired under warranty, use:

Labor Operation Description Labor Time
4020470Air Cleaner Element ReplacementUse Published Labor Operation Time
4020390Air Cleaner Assembly Replacement


ModifiedMay 31, 2016 – Added repair as needed for codes P0420, P0430 in Correction.


GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer".* They are written to inform these technicians of



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